git fetch origin --prune doesn't delete local branches?
At one point I thought that git fetch origin --prune deleted local branches that were no longer present on the server. Somehow this is not my experience at the moment.
I ran this command, and the local branch was not deleted. It is not currently checked out. I ran git branch -vv to check this info, and I see
feature/MyGreatFeature f30efc7 [origin/feature/MyGreatFeature: gone]
So it seems to know that it is gone. Why would it not delete my local branch?
Running git version 2.7.4 (Apple Git-66)
Answer
The various prune options (git remote update --prune, git remote prune, git fetch --prune) only delete remote-tracking branches.1
You'll need to manually delete local branches you no longer want, or change or remove their upstream setting if the remote-tracking branch no longer exists. Note that each local branch can record a remote and/or branch that do not now, or even never did, exist. In this case Git mostly acts as if those local branches have no upstream set, except that since version 1.8.5, several commands report the upstream as "gone" or otherwise invalid, and may suggest using --unset-upstream.
1More precisely, they delete destination refs after doing the refspec mapping from the command line or fetch lines from the configuration. Hence, for fetch mirrors, they can delete local branches. Most clones are not set up as fetch mirrors, though.
There were some recent bug fixes for complex mappings, to make sure that Git did not prune a mapped branch in some cases when it should not. For any normal repository—ordinary clone or pure fetch mirror—these fixes have no effect; they matter only if you have complicated fetch configurations.