My git repository has two branches, master and bug. I want to create a branch bug/rep. So I run :

git branch bug/rep

This gives the error:

error: unable to resolve reference refs/heads/bug/rep: Not a directory fatal: Cannot lock the ref 'refs/heads/bug/rep'.

How can I create a sub branch from the bug branch, like bug/rep? My git version is 2.3.2 on the Mac.