This code I'm reverting works. But it has a problem: The export db and
log and the ContentIdentifier db and log still list the content as being
stored in the remote. So when I ran borg create again and stored the
content in borg again in a new archive, git-annex sync noticed that, but
since it didn't update the tree for the old archives, it then thought
the content that had been removed from them was still in them, and so
git-annex get failed in an ugly way:
Include pattern 'tmp/x/.git/annex/objects/pX/ZJ/SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855/SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855' never matched.
[2020-12-28 16:40:44.878952393] process [933616] done ExitFailure 1
user error (borg ["extract","/tmp/b::abs4","tmp/x/.git/annex/objects/pX/ZJ/SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855/SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"] exited 1)
It does not seem worth it to update the git tree for the export when dropping
content, that would make drop of many files very expensive in git tree objects
created. So, let's not support this I suppose..
Especially from borg, where the content identifier logs
all end up being the same identical file!
But also, for other imports, the location tracking logs can,
in some cases, be identical files.
Bonus optimisation: Avoid looking up (and parsing when set)
GIT_ANNEX_VECTOR_CLOCK env var every time a log is written to.
Although the lookup does happen at startup even when no
log will be written now.
For reasons explained in the bug report.
Implemented using a persistent migration, which works fine. It may add a
little startup overhead when a remote is enabled that uses this, but
probably un-noticable.
On the next major version, it would be fine to delete this database,
and regenerate it from the git-annex branch information. Then this
change could be reverted.
Did nothing about adding back the data that got dropped from the db
due to the bug. Only the borg special remote was probably affected,
and it's not been released yet. rm -rf .git/annex/cidsdb does work.
