Added annex.skipunknown git config, that can be set to false to change the
behavior of commands like `git annex get foo*`, to not skip over files/dirs
that are not checked into git and are explicitly listed in the command
line.
Significant complexity was needed to handle git-annex add, which uses some
git ls-files calls, but needs to not use --error-unmatch because of course
the files are not known to git.
annex.skipunknown is planned to change to default to false in a
git-annex release in early 2022. There's a todo for that.
Fix a crash or potentially not all files being exported when sync -J
--content is used with an export remote.
Crash as described in fixed bug report.
waitForAllRunningCommandActions inserted in several points where all the
commandActions started before need to have finished before moving on to
the next stage of the export. A race across those points could have
maybe resulted in not all files being exported, or a wrong tree being
export.
For example, changeExport starting up an action like
a rename of A to B. Then, with that action still running, fillExport
uploading a new A, *before* the rename occurred. That race seems
unlikely to have happened. There are some other ones that this also
fixes.
This relicates git's behavior. It adds a few stat calls for the command
line parameters, so there is some minor slowdown, but even with thousands
of parameters it will not be very noticable, and git does the same statting
in similar circumstances.
Note that this does not prevent eg "git annex add symlink"; the symlink
will be added to git as usual. And "git annex find symlink" will silently
list nothing as well. It's only "symlink/foo" or "subdir/symlink/foo" that
triggers the warning.
Avoid running a large number of git cat-file child processes when run with
a large -J value.
This implementation takes care to avoid adding any overhead to git-annex
when run without -J. When run with -J, there is a small bit of added
overhead, to manipulate the resource pool. That optimisation added a
fair bit of complexity.
This does mean that RemoteDaemon.Transport.Tor's call runs it, otherwise
no change, but this is groundwork for doing more such expensive actions
in dupState.
Git has an obnoxious special case in git config, a line "foo" is the same
as "foo = true". That means there is no way to examine the output of
git config and tell if it was run with --null or not, since a "foo"
in the first line could be such a boolean, or could be followed by its
value on the next line if --null were used.
So, rather than trying to do such a detection, track the style of config
at all the points where it's generated.
The only price paid is one additional MVar read per write to the journal.
Presumably writing a journal file dominiates over a MVar read time by
several orders of magnitude.
--batch does not get the speedup because then it needs to notice when
another process has made a change. Also made the assistant and other damon
modes bypass the optimisation, which would not help them anyway.
The 'fail' method has been moved to the 'MonadFail' class. I made the changes
so that the code still compiles with previous versions of 'base' that don't
have the new MonadFail class exported by Prelude yet.
It's important that it be clear that it overrides a config, such that
reloading the git config won't change it, and in particular, setConfig
won't change it.
Most of the calls to changeGitConfig were actually after setConfig,
which was redundant and unncessary. So removed those.
The only remaining one, besides --debug, is in the handling of
repository-global config values. That one's ok, because the
way mergeGitConfig is implemented, it does not override any value that
is set in git config. If a value with a repo-global setting was passed
to setConfig, it would set it in the git config, reload the git config,
re-apply mergeGitConfig, and use the newly set value, which is the right
thing.
The git add behavior changes could be avoided if it turns out to be
really annoying, but then it would need to behave the old way when
annex.dotfiles=false and the new way when annex.dotfiles=true. I'd
rather not have the config option result in such divergent behavior as
`git annex add .` skipping a dotfile (old) vs adding to annex (new).
Note that the assistant always adds dotfiles to the annex.
This is surprising, but not new behavior. Might be worth making it also
honor annex.dotfiles, but I wonder if perhaps some user somewhere uses
it and keeps large files in a directory that happens to begin with a
dot. Since dotfiles and dotdirs are a unix culture thing, and the
assistant users may not be part of that culture, it seems best to keep
its current behavior for now.
git-annex find is now RawFilePath end to end, no string conversions.
So is git-annex get when it does not need to get anything.
So this is a major milestone on optimisation.
Benchmarks indicate around 30% speedup in both commands.
Probably many other performance improvements. All or nearly all places
where a file is statted use RawFilePath now.
Adds a dependency on filepath-bytestring, an as yet unreleased fork of
filepath that operates on RawFilePath.
Git.Repo also changed to use RawFilePath for the path to the repo.
This does eliminate some RawFilePath -> FilePath -> RawFilePath
conversions. And filepath-bytestring's </> is probably faster.
But I don't expect a major performance improvement from this.
This is mostly groundwork for making Annex.Location use RawFilePath,
which will allow for a conversion-free pipleline.
The parser and looking up config keys in the map should both be faster
due to using ByteString.
I had hoped this would speed up startup time, but any improvement to
that was too small to measure. Seems worth keeping though.
Note that the parser breaks up the ByteString, but a config map ends up
pointing to the config as read, which is retained in memory until every
value from it is no longer used. This can change memory usage
patterns marginally, but won't affect git-annex.
Finally builds (oh the agoncy of making it build), but still very
unmergable, only Command.Find is included and lots of stuff is badly
hacked to make it compile.
Benchmarking vs master, this git-annex find is significantly faster!
Specifically:
num files old new speedup
48500 4.77 3.73 28%
12500 1.36 1.02 66%
20 0.075 0.074 0% (so startup time is unchanged)
That's without really finishing the optimization. Things still to do:
* Eliminate all the fromRawFilePath, toRawFilePath, encodeBS,
decodeBS conversions.
* Use versions of IO actions like getFileStatus that take a RawFilePath.
* Eliminate some Data.ByteString.Lazy.toStrict, which is a slow copy.
* Use ByteString for parsing git config to speed up startup.
It's likely several of those will speed up git-annex find further.
And other commands will certianly benefit even more.
Goal is to make git-annex faster by using ByteString for all the
worktree traversal. For now, this is focusing on Command.Find,
in order to benchmark how much it helps. (All other commands are
temporarily disabled)
Currently in a very bad unbuildable in-between state.
See the comment for a trace of the deadlock.
Added a new StartStage. New worker threads begin in the StartStage.
Once a thread is ready to do work, it moves away from the StartStage,
and no thread will ever transition back to it.
A thread that blocks waiting on another thread that is processing
the same key will block while in the StartStage. That other thread
will never switch back to the StartStage, and so the deadlock is avoided.
Drop support for building with ghc older than 8.4.4, and with older
versions of serveral haskell libraries than will be included in Debian 10.
The only remaining version ifdefs in the entire code base are now a couple
for aws!
This commit should only be merged after the Debian 10 release.
And perhaps it will need to wait longer than that; it would make
backporting new versions of git-annex to Debian 9 (stretch) which
has been actively happening as recently as this year.
This commit was sponsored by Ilya Shlyakhter.
When all worker threads are running and enteringStage is called,
it waits for an idle slot. If all off the other threads then call it in
turn, a deadlock occurrs.
This is the same problem I didn't actually fix in
5a9842d7ed.
Fixed by doing two separate STM transactions, the first replaces its
active thread with an idle thread, and the second waits for another idle
thread. That guarantees there will eventually be an idle thread to find.
The changes to WorkerPool were necessary because it can't add an idle
thread containing the Annex state and go on to run an action using that
same state, so I had to remove the Annex state from IdleWorker.
Rather than limiting it to PerformStage and CleanupStage, this opens it
up so any number of stages can be added as needed by commands.
Each concurrent command has a set of stages that it uses, and only
transitions between those can block waiting for a free slot in the
worker pool. Calling enteringStage for some other stage does not block,
and has very little overhead.
Note that while before the Annex state was duplicated on the first call
to commandAction, this now happens earlier, in startConcurrency.
That means that seek stage actions should that use startConcurrency
and then modify Annex state won't modify the state of worker threads
they then start. I audited all of them, and only Command.Seek
did so; prepMerge changes the working directory and so has to come
before startConcurrency.
Also, the remote list is built before duplicating the state, which means
that it gets built earlier now than it used to. This would only have an
effect of making commands that end up not needing to perform any actions
unncessary build the remote list (only when they're run with concurrency
enable), but that's a minor overhead compared to commands seeking
through the work tree and determining they don't need to do anything.
I couldn't find a way to avoid the deadlock w/o rewriting it to clearly
not have one. I'm not quite sure what was the actual cause of the
deadlock.
This makes me unsure how I now know it clearly doesn't have a
deadlock. But, it was easy to reproduce before (just call it twice in a
row) and doesn't happen now.
Oh joyous day, this is probably git-annex's oldest implementation wart,
source of much unncessary bother.
Now that we have a StartMessage, showEndResult' can look at it to know
if it needs to display an end message or not.
This is also going to be faster, because it avoids an uncessary state
lookup for each file processed.
The hoped for optimisation of CommandStart with -J did not materialize.
In fact, not runnign CommandStart in parallel is slower than -J3.
So, CommandStart are still run in parallel.
(The actual bad performance I've been seeing with -J in my big repo
has to do with building the remoteList.)
But, this is still progress toward making -J faster, because it gets rid
of the onlyActionOn roadblock in the way of making CommandCleanup jobs
run separate from CommandPerform jobs.
Added OnlyActionOn constructor for ActionItem which fixes the
onlyActionOn breakage in the last commit.
Made CustomOutput include an ActionItem, so even things using it can
specify OnlyActionOn.
In Command.Move and Command.Sync, there were CommandStarts that used
includeCommandAction, so output messages, which is no longer allowed.
Fixed by using startingCustomOutput, but that's still not quite right,
since it prevents message display for the includeCommandAction run
inside it too.
The goal is to be able to run CommandStart in the main thread when -J is
used, rather than unncessarily passing it off to a worker thread, which
incurs overhead that is signficant when the CommandStart is going to
quickly decide to stop.
To do that, the message it displays needs to be displayed in the worker
thread, after the CommandStart has run.
Also, the change will mean that CommandStart will no longer necessarily
run with the same Annex state as CommandPerform. While its docs already
said it should avoid modifying Annex state, I audited all the
CommandStart code as part of the conversion. (Note that CommandSeek
already sometimes runs with a different Annex state, and that has not been
a source of any problems, so I am not too worried that this change will
lead to breakage going forward.)
The only modification of Annex state I found was it calling
allowMessages in some Commands that default to noMessages. Dealt with
that by adding a startCustomOutput and a startingUsualMessages.
This lets a command start with noMessages and then select the output it
wants for each CommandStart.
One bit of breakage: onlyActionOn has been removed from commands that used it.
The plan is that, since a StartMessage contains an ActionItem,
when a Key can be extracted from that, the parallel job runner can
run onlyActionOn' automatically. Then commands won't need to worry about
this detail. Future work.
Otherwise, this was a fairly straightforward process of making each
CommandStart compile again. Hopefully other behavior changes were mostly
avoided.
In a few cases, a command had a CommandStart that called a CommandPerform
that then called showStart multiple times. I have collapsed those
down to a single start action. The main command to perhaps suffer from it
is Command.Direct, which used to show a start for each file, and no
longer does.
Another minor behavior change is that some commands used showStart
before, but had an associated file and a Key available, so were changed
to ShowStart with an ActionItemAssociatedFile. That will not change the
normal output or behavior, but --json output will now include the key.
This should not break it for anyone using a real json parser.
659640e224 was buggy, it had a STM
deadlock because two actions both wanted to takeTMVar the WorkerPool
and so blocked one-another.
Fixed by completely reworking how the pool is maintained. Maintenace
threads now wait for the Async actions and update the WorkerPool. This
means twice as many threads as before, but green threads so will only
use a few extra bytes ram per thread.
When running multiple concurrent actions, the cleanup phase is run in a
separate queue than the main action queue. This can make some commands
faster, because less time is spent on bookkeeping in between each file
transfer.
But as far as I can see, nothing will be sped up much by this yet, because
all the existing cleanup actions are very light-weight. This is just groundwork
for deferring checksum verification to cleanup time.
This change does mean that if the user expects -J2 will mean that they see no
more than 2 jobs running at a time, they may be surprised to see 4 in some
cases (if the cleanup actions are slow enough to notice).
It might also make sense to enable background cleanup without the -J,
for at least one cleanup action. Indeed, that's the behavior that -J1
has now. At some point in the future, it make make sense to make the
behavior with no -J the same as -J1. The only reason it's not currently
is that git-annex can build w/o concurrent-output, and also any bugs
in concurrent-output (such as perhaps misbehaving on non-VT100 compatible
terminals) are avoided by default by only using it when -J is used.
Added the ability to run one job per CPU (core), by setting annex.jobs=cpus,
or using option --jobs=cpus or -Jcpus.
Built with future expansion in mind, including not defaulting matching on
Concurrency so more constructors can later be added, and using "cpu"
instead of "0".
This does not change the overall license of the git-annex program, which
was already AGPL due to a number of sources files being AGPL already.
Legally speaking, I'm adding a new license under which these files are
now available; I already released their current contents under the GPL
license. Now they're dual licensed GPL and AGPL. However, I intend
for all my future changes to these files to only be released under the
AGPL license, and I won't be tracking the dual licensing status, so I'm
simply changing the license statement to say it's AGPL.
(In some cases, others wrote parts of the code of a file and released it
under the GPL; but in all cases I have contributed a significant portion
of the code in each file and it's that code that is getting the AGPL
license; the GPL license of other contributors allows combining with
AGPL code.)
Added graftTree but it's buggy.
Should use graftTree in Annex.Branch.graftTreeish; it will be faster
than the current implementation there.
Started Annex.Import, but untested and it doesn't yet handle tree
grafting.
* fromkey: Added --json.
* fromkey --batch output changed to support using it with --json.
The old output was not parseable for any useful information, so
this is not expected to break anything.
No deprecation warning at run time, just one on the man page.
One thing findref remains able to do that find cannot is to run in a bare
repo. Find was made to refuse to run in a bare repo because it seemed
confusing for it to not list any files ever in that situation. It would be
better for find --branch to work in a bare repo but not without --branch
but I don't currently have a way to do that.
Probably a better solution would be to make git-annex in a bare repo
default to --branch master or something like that instead of --all.
This commit was sponsored by Denis Dzyubenko on Patreon.
* findref: Support file matching options: --include, --exclude,
--want-get, --want-drop, --largerthan, --smallerthan, --accessedwithin
* Commands supporting --branch now apply file matching options --include,
--exclude, --want-get, --want-drop to filenames from the branch.
Previously, combining --branch with those would fail to match anything.
* add, import, findref: Support --time-limit.
This commit was sponsored by Jake Vosloo on Patreon.
When a command is operating on multiple files and there's an error with
one, try harder to continue to the rest. (As was already done for many
types of errors including IO errors.)
This handles cases like lockContentForRemoval throwing an exception when
the content is already locked. Just because a drop of one file fails, does
not mean it shouldn't go on to try to drop other files.
I looked over uses of `giveup` in Command/*; there are too many to check
them all extensively, but none stood out as being problems that should let
one commandAction stop running other commandActions. Worst case, something
bad will happen and rather than stopping right away with an error,
git-annex will display multiple errors as it fails over and over on each
file. I don't think I ever really intended `error`/`giveup` to stop other
commandActions; this was a relic of old confusion over haskell exception
handling.
Test suite passes.
This commit was sponsored by Ethan Aubin.
Of course, it wasn't used much in those modes, because normal output is
avoided. But it was still initialized and used in a few places,
including a call to hideRegionsWhile.
This relies on git ls-files --with-tree, which I'm using in a way that
its man page does not document. Hm. I emailed the git list to try to get
the docs improved, but at least the git test suite does test the same
kind of use case I'm using here.
Performance impact when not in an adjusted branch is limited to some
additional MVar accesses, and a single git call to determine the name of
the current branch. So very minimal.
When in an adjusted branch, the performance impact is
in Annex.WorkTree.lookupFile, which starts doing an equal amount of work
for files that didn't exist as it already did for files that were
unlocked.
This commit was sponsored by Jochen Bartl on Patreon.
Running git-annex linux builds in termux seems to work well enough that the
only reason to keep the Android app would be to support Android 4-5, which
the old Android app supported, and which I don't know if the termux method
works on (although I see no reason why it would not).
According to [1], Android 4-5 remains on around 29% of devices, down from
51% one year ago.
[1] https://www.statista.com/statistics/271774/share-of-android-platforms-on-mobile-devices-with-android-os/
This is a rather large commit, but mostly very straightfoward removal of
android ifdefs and patches and associated cruft.
Also, removed support for building with very old ghc < 8.0.1, and with
yesod < 1.4.3, and without concurrent-output, which were only being used
by the cross build.
Some documentation specific to the Android app (screenshots etc) needs
to be updated still.
This commit was sponsored by Brett Eisenberg on Patreon.
Added annex.jobs setting, which is like using the -J option.
Of course, -J overrides annex.jobs.
This commit was sponsored by Trenton Cronholm on Patreon.
This is groundwork for nested seek loops, eg seeking over all files and
then performing commandActions on a list of remotes, which can be done
concurrently.
This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
Same goal as b18fb1e343 but without
breaking backwards compatability. Just return IO exceptions when running
the P2P protocol, so that git-annex-shell can detect eof and avoid the
ugly message.
This commit was sponsored by Ethan Aubin.
Added -z option to git-annex commands that use --batch, useful for
supporting filenames containing newlines.
It only controls input to --batch, the output will still be line delimited
unless --json or etc is used to get some other output. While git often
makes -z affect both input and output, I don't like trying them together,
and making it affect output would have been a significant complication,
and also git-annex output is generally not intended to be machine parsed,
unless using --json or a format option.
Commands that take pairs like "file key" still separate them with a space
in --batch mode. All such commands take care to support filenames with
spaces when parsing that, so there was no need to change it, and it would
have needed significant changes to the batch machinery to separate tose
with a null.
To make fromkey and registerurl support -z, I had to give them a --batch
option. The implicit batch mode they enter when not provided with input
parameters does not support -z as that would have complicated option
parsing. Seemed better to move these toward using the same --batch as
everything else, though the implicit batch mode can still be used.
This commit was sponsored by Ole-Morten Duesund on Patreon.
The new second pass sees the file as type changed because the first
pass's changes have typically not reached git yet. So, have to
explicitly check for unmodified files in the second pass.
Note that, if the file has been touched but not really modified,
the first pass will handle it, and so the second pass does nothing.
This commit was sponsored by Jochen Bartl on Patreon.
v6: When a file is unlocked but has not been modified, and the unlocking is
only staged, git-annex add did not lock it. Now it will, for consistency
with how modified files are handled and with v5.
Note the removal of the sameInodeCache check. Otherwise it would see
that the unmodified file is unmodified and stop there. That check seems to have
been copied from the direct mode branch. But, direct mode had a specific
reason to check for unmodified content, that does not apply to v6.
The second pass means there is potential for a race, eg the unlocked
file could be modified in between the first and second passes.
No problem with that, since both passes do the same thing.
This commit was sponsored by Jake Vosloo on Patreon.
When --batch is used with matching options like --in, --metadata, etc, only
operate on the provided files when they match those options. Otherwise, a
blank line is output in the batch protocol.
Affected commands: find, add, whereis, drop, copy, move, get
In the case of find, the documentation for --batch already said it honored
the matching options. The docs for the rest didn't, but it makes sense to
have them honor them. While this is a behavior change, why specify the
matching options with --batch if you didn't want them to apply?
Note that the batch output for all of the affected commands could
already output a blank line in other cases, so batch users should
already be prepared to deal with it.
git-annex metadata didn't seem worth making support the matching options,
since all it does is output metadata or set metadata, the use cases for
using it in combination with the martching options seem small. Made it
refuse to run when they're combined, leaving open the possibility for later
support if a use case develops.
This commit was sponsored by Brett Eisenberg on Patreon.
Useful for dropping old objects from cache repositories.
But also, quite a genrally useful thing to have..
Rather than imitiating find's -atime and other options, all of which are
pretty horrible to use, I made this match files accessed within a time
period, using the same duration format used by git-annex schedule and
--limit-time
In passing, changed the --limit-time option parser to parse the
duration, instead of having it later throw an error.
This commit was supported by the NSF-funded DataLad project.
Makes it allow writes, but not deletion of annexed content. Note that
securing pushes to the git repository is left up to the user.
This commit was sponsored by Jack Hill on Patreon.
In Annex.Branch.branch, the (++) was killing laziness.
Rewrote so it streams lazily.
filterM also kills laziness, so made loggedKeys use a Unchecked type,
and check if the key is dead in the seek loop.
Note that loggedKeysFor still buffers, so git-annex info <remote> and
git-annex unused --from remote still use more memory than necessary.
Also removed some unused functions from Annex.Journal.
Test case is 24 directories each containing files named 1..10000.
The concat and filterM destroyed what laziness there is in
dirContentsRecursive, making it buffer all the filenames. Memory
use was around 300 mb (possibly growing slightly as it progressed).
After this fix, memory use drops to a constant 59 mb.
Note that dirContentsRecursive still buffers the entire content of a
directory (not subdirectories) so this is still not optimal.
Unfortunately ReceiveMessage didn't handle unknown messages the way it
was documented to; client sending VERSION would cause the server to
return an ERROR and hang up. Fixed that, but old releases of git-annex
use the P2P protocol for tor and will still have that behavior.
So, version is not negotiated for Remote.P2P connections, only for
Remote.Git connections, which will support VERSION from their first
release. There will need to be a later flag day to change Remote.P2P;
left a commented out line that is the only thing that will need to be
changed then.
Version 1 of the P2P protocol is not implemented yet, but updated
the docs for the DATA change that will be allowed by that version.
This commit was sponsored by Jeff Goeke-Smith on Patreon.
Not yet used by git-annex, but this will allow faster transfers etc than
using individual ssh connections and rsync.
Not called git-annex-shell p2p, because git-annex p2p does something
else and I don't want two subcommands with the same name between the two
for sanity reasons.
This commit was sponsored by Øyvind Andersen Holm.
Added --json-error-messages option, which includes error messages in the
json output, rather than outputting them to stderr.
The actual rediretion of errors is not implemented yet, this is only
the docs and option plumbing.
This commit was supported by the NSF-funded DataLad project.
Fix behavior of --json-progress followed by --json, in which
the latter option disabled the former.
This commit was supported by the NSF-funded DataLad project.
And for tab completion, by not unnessessarily statting paths to remotes,
which used to cause eg, spin-up of removable drives.
Got rid of the remotes member of Git.Repo. This was a bit painful.
Remote.Git modifies the list of remotes as it reads their configs,
so still need a persistent list of remotes. So, put it in as
Annex.gitremotes. It's only populated by getGitRemotes, so commands
like examinekey that don't care about remotes won't do so.
This commit was sponsored by Jake Vosloo on Patreon.
Chose to make this only handle files actively being downloaded, not temp
files for downloads that were interrupted or files that have been fully
downloaded.
This commit was sponsored by Ole-Morten Duesund on Patreon.
Test suite is always included.
Building with this flag disabled has actually been broken for some time,
since Command.TestRemote uses tasty. Fewer build flags are better, so good
time to drop it.
This commit was sponsored by Thomas Hochstein on Patreon.
This avoids all the complication about redundant work discussed in
the previous try at fixing this. At the expense of needing each command
that could have the problem to be patched to simply wrap the action in
onlyActionOn once the key is known. But there do not seem to be many
such commands.
onlyActionOn' should not be used with a CommandStart (or CommandPerform),
although the types do allow it. onlyActionOn handles running the whole
CommandStart chain. I couldn't immediately see a way to avoid mistken
use of onlyActionOn'.
This commit was supported by the NSF-funded DataLad project.
git annex add, git annex lock etc make multiple seek passes,
and each seek pass checked that files existed. That was unncessary
redundant work.
Fixed by adding a new WorkTreeItem type, make seek actions use it,
and check that the files exist when constructing it.
This commit was supported by the NSF-funded DataLad project.
optparse-applicative-0.14.0.0 adds support for these, so have the
Makefile install their scripts when built with it.
CmdLine/GitAnnex/Options.hs now uses action "file" in cmdParams,
which affects the bash and zsh completions, letting them complete
filenames for subcommands that use that. This is not needed for
bash, since bash-completion.bash enables -o bashdefault, which
lets it complete filenames too. But it does not seem to break the bash
completions. It is needed for zsh; the zsh completion otherwise
does not complete filenames. The fish completion will always complete
filenames no matter what. Messy.
This commit was sponsored by Denis Dzyubenko on Patreon.
When setting metadata of a file that did not exist, no error message was
displayed, unlike getting metadata and most other git-annex commands. Fixed
this oversight.
Note that, if the file exists but is not annexed, there's no error.
This is the same behavior as other git-annex commands.
This commit was supported by the NSF-funded DataLad project.
Reworked remote name parsing to allow things like that. Command.Move
uses it for --to=here, although there's not yet an implementation of
that option.
This commit was sponsored by Ignacio on Patreon.
See my comment. This only avoids the problem for -J; two git-annex
processes started at the same time could still both try to write to
.git/config and one fail. That would be very unlikely though, and it
doesn't really seem worth adding an additional layer of locking around
.git/config.
This commit was supported by the NSF-funded DataLad project.
