This has tradeoffs, but is generally a win, and users who it causes git add to
slow down unacceptably for can just disable it again.
It needed to happen in an upgrade, since there are git-annex versions
that do not support it, and using such an old version with a v8
repository with filter.annex.process set will cause bad behavior.
By enabling it in v9, it's guaranteed that any git-annex version that
can use the repository does support it. Although, this is not a perfect
protection against problems, since an old git-annex version, if it's
used with a v9 repository, will cause git add to try to run
git-annex filter-process, which will fail. But at least, the user is
unlikely to have an old git-annex in path if they are using a v9
repository, since it won't work in that repository.
Sponsored-by: Dartmouth College's Datalad project
git-annex allows managing large files with git, without storing the file
contents in git. It can sync, backup, and archive your data, offline
and online. Checksums and encryption keep your data safe and secure. Bring
the power and distributed nature of git to bear on your large files with
git-annex.
For documentation, see doc/ or <https://git-annex.branchable.com/>