This is a todo for collecting changes that could lead to a v11 repository version.

• Append to journal files even when annex.alwayscompact=true. This can make it a lot faster in some cases. See note in Annex.Branch.changeOrAppend.

  It's important that this only happen when no git-annex version older than 10.20220724 can plausibly be running in a repository after upgrading to the repo version that enables this. Depending on the timing of v11, this may need to be put in a v12 upgrade that is delayed some amount of time (eg 1 year) after v11.

• Avoid locking old transfer lock file. transferFileAndLockFile currently returns two lock files for Download transfers, and locking both of them is unncessary work, which is only needed to interoperate with old git-annex versions that only lock the old lock file and not the new one.

  See f04d9574d6a56cfdf034a974f9714f0a3b8c49fa.

  (Note that the old lock file should still be deleted when cleaning up the new lock file, to make sure that all the old lock files get deleted.)

  It would not be great if this change were made when a git-annex version 10.20240227 or older was running in the repository. But it wouldn't be the end of the world either, because the effect would be effectively the same as the bug that the second transfer lock was added to fix. Still, it would make sense to put this in a v12 upgrade that is delayed some amount of time (eg 1 year) after v11.