Please describe the problem.
When a repository created shared pre 5.20151208 is fsck'd, it spews error messages a la
setFileMode: permission denied (Operation not permitted) and fails the fsck.
This seems to be due to the change in file permissions introduced in("When core.sharedRepository is set, annex object files are not made mode 444, since that prevents a user other than the file owner from locking them. Instead, a mode such as 664 is used in this case."). The error message is unclear to a user, though, and does IMO not constitute an error to fail over.
IMO, failure to set the mode due to ownership issues should be ignored in fsck, and when a user other than the original owner tries to lock a file, they should be presented with an error message a la "Please run
git annex fsck --fast as to fix the file's permissions". As an alternative or additionally, fsck could show a warning (maybe even an error) that running an additional fsck as all of the other users (explicit list would be nice) to fix all file permissions.
The issue can be resolved for a repository by
What version of git-annex are you using? On what operating system?
This was observed on a git-annex remote pushed to via ssh on debian sid, with pushes from various git-annex versions over the past years.