Merge branch 'jk/branch-shortening-funny-symrefs' into maint

A change back in version 2.7 to "git branch" broke display of a symbolic ref in a non-standard place in the refs/ hierarchy (we expect symbolic refs to appear in refs/remotes/*/HEAD to point at the primary branch the remote has, and as .git/HEAD to point at the branch we locally checked out). * jk/branch-shortening-funny-symrefs: branch: fix shortening of non-remote symrefs