Avoid a warning message when renameExport is not supported, and just
fallback to deleting with a subsequent re-upload. Especially needed for
importtree remotes, where renameExport needs to be disabled.
This changes the external special remote protocol, but in a
backwards-compatible way. A reply of UNSUPPORTED-REQUEST to an older
version of git-annex will cause it to make renameExport return False.
This works, and tested syncing both gets changes from a special remote
and sends changes to it, keeping it fully in sync nicely!
But have not tried it with a subdir configured.
Users may want sync to only export, or only import and this is broadly
analagous to push and pull, so it makes sense to use the same
configuration for it.
This is not super efficient; it would be better to lock the database
once and build up a queue of changes and flush once.
But, storeExportWithContentIdentifier is likely going to be the really
expensive part, so let's do the simple thing and only optimise later if
needed.
untested
This won't be super slow, but it does need to diff two likely large
trees, and since the git-annex branch rarely sits still, it will most
likely be run at the beginning of every import.
A possible speed improvement would be to only run this when the database
did not contain a ContentIdentifier. But that would only speed up
imports when there is no new version of a file on the special remote,
at most renames of existing files being imported.
A better speed improvement would be to record something in the git-annex
branch that indicates when an import has been run, and only do the diff
if the git-annex branch has record of a newer import than we've seen
before. Then, it would only run when there is in fact new
ContentIdentifier information available from a remote. Certianly doable,
but didn't want to complicate things yet.
locationLogFileKey had an out of date list of toplevel log files to skip
over, and was only not broken because the other toplevel log files don't
look like keys. Fixed that too.
Note that I tried an evil remote that lists ImportLocations with
../../../ in them and indeed this resulted in git blowing up and the
import failing, and not writing outside the repo.
An empty list of [ContentIdenfier] serialized to the same thing
as a single ContentIdentifier "". Avoid this ambiguity by requiring the
list be non-empty.
Alternative doesn't combine the subparsers the way I wanted.
Unfortunately this new parser has suboptimal usage because everything is
all jumbled together.
