[[!comment format=mdwn
 username="joey"
 subject="""comment 11"""
 date="2022-01-12T19:40:35Z"
 content="""
This is going to need two repository version bumps:

v9:  Add the upgrade lock file, and all git-annex processes take a shared
lock to avoid the repository being upgraded out from under them.

v10: Skipped until the upgrade lock file is of a certain age. Take upgrade
lock before upgrading.

In v10, stop locking content files and lock separate lock files.

The age could be eg 1 month, which assumes that no pre-v9 git-annex
process like `git-annex move --to remote` is still running after that long.
Of course, that is still an assumption, but it can be pushed out as long as
it takes to feel comfortable with it. Maybe 1 year? The only disadvantage
really is that any v11 upgrade would also get deferred.

Since the assistant can possibly run for longer than a year without
restarting, the v10 upgrade would need to be skipped when the assistant is
running.

`git-annex upgrade --version=10` could be available to speed up that
upgrade. The user would be responsible for making sure there are no such
old git-annex processes running, so that might need --force.
"""]]
