I'm trying to sync from a direct repo to another direct repo but getting a non-fast-forward rejection:

push v-crateris 
Counting objects: 509, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (455/455), done.
Writing objects: 100% (509/509), 33.21 KiB | 4.74 MiB/s, done.
Total 509 (delta 350), reused 0 (delta 0)
remote: Resolving deltas: 100% (350/350), completed with 174 local objects.
To v-crateris:/annex/Music
   c60621302..803920707  git-annex -> synced/git-annex
 ! [rejected]            annex/direct/master -> synced/master (non-fast-forward)
error: failed to push some refs to 'v-crateris:/annex/Music'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. Check out this branch and integrate the remote changes
hint: (e.g. 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
To v-crateris:/annex/Music
 ! [rejected]            master -> master (non-fast-forward)
error: failed to push some refs to 'v-crateris:/annex/Music'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. Check out this branch and integrate the remote changes
hint: (e.g. 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

  Pushing to v-crateris failed.

  (non-fast-forward problems can be solved by setting receive.denyNonFastforwards to false in the remote's git config)
failed

I tried setting receive.denyNonFastforwards to false as the message said, but it made no difference. Both repos have annex/direct/master checked out.

What should I do to resolve this?