I'm using git with zsh
when I type in 'gco' and press the 'tab' key, it will be like the following
Those are not deleted or merged branches, but I don't want them.
Especially something like
7038cc34 -- [HEAD]
Make sure to use the latest Git 2.13, which improved on Git completion:
In your case, check the git branch -avv output to see if those "branches" are listed at all. If not, it could be a new bug to report to the mailing list.
git branch -avv