export, sync --content: Avoid unnecessarily trying to upload files to an
exporttree remote that already contains the files.
When the export was origianly made in one repo and now git-annex is
running in a different repo, the export database is not yet populated with
information about the exportLocation of files. So, it was trying to upload
the files to the export, even when it already contained them.
sync --content would first download the content from the export, and then
re-upload the content back.
And this also led to "not available" failures for each file that was not
locally present yet.
Fix: Just use checkPresentExport before uploading; if it succeeds update
the database.
This is a surprising oversight, it's possible it fixes a reversion because
I would have thought I'd have noticed this problem when originally
developing exporttree remotes.
This commit was sponsored by Jochen Bartl on Patreon.
git-annex allows managing files with git, without checking the file
contents into git. While that may seem paradoxical, it is useful when
dealing with files larger than git can currently easily handle, whether due
to limitations in memory, checksumming time, or disk space.
For documentation, see doc/ or <https://git-annex.branchable.com/>
c3fa1f2b08