Fix for misleading "missing delta bases" error - Fix #2721.
Merge pull request #2723 from ravindp/ravindp/fix_4_missing_delta_bases

Fix for misleading "missing delta bases" error.
Fixed deleting refs in local remotes not working anymore

This fixes a regression introduced in aad638f3a1e4d98296c2ec9c4ed08f217a652c5c
where pushing a refspec with an empty left component to delete a ref in a
remote that is a local bare repository would fail.