I have a repo hosted in Github. The command git branch -a shows the following:
* develop
  master
  remotes/origin/HEAD -> origin/master
  remotes/origin/develop
  remotes/origin/master
  remotes/origin/release-031
The (old) release-031 is not present in the Github repo, and I can not delete it locally either:
$ git branch -d release-031
error: branch 'release-031' not found.
How can I remove these phantom old branch?
