An engineer reported this issue with arc land:
"arc just deleted my local branch after failing to land/merge it"
BUILDS PASSED Harbormaster builds for the active diff completed successfully.
PUSHING Pushing changes to "origin/master".
! [rejected] 3f290cae1df8107b42ad38bb7cc656dca9e8edc6 -> master (fetch first)
error: failed to push some refs to 'ssh://firstname.lastname@example.org/diffusion/P/Pinboard.git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first 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.
Local "master" tracks target remote "origin/master", checking out and pulling changes.
Cleaning up branch "address_validation"...
(Use `git checkout -b address_validation d89181e7fc14553d02f3a191c97884ebdf17f90f` if you want it back.)
DONE Landed changes.