adjusted branches: submodule deletions not propagated on sync

[kyleam]

While looking into an adjusted branch-related test failure today, I noticed that calling datalad remove <subdataset> on an adjusted branch didn't register the deletion in the main branch. I'm opening an issue here just as a heads up; I've reported the bug along with a potential fix on git-annex's side:

https://git-annex.branchable.com/bugs/Submodule_deletion_not_synced_from_adjusted_branch/

Unfortunately I don't see an easy way we could address this on our end for older git-annex versions.

Re: #4292

[kyleam]

Fixed by 8.20201129-78-gfd161da2c (adjustTree: Consider submodule deletions, 2021-01-06).