Merge branch 'jt/refspec-dwim-precedence-fix'

"git fetch $there refs/heads/s" ought to fetch the tip of the branch 's', but when "refs/heads/refs/heads/s", i.e. a branch whose name is "refs/heads/s" exists at the same time, fetched that one instead by mistake. This has been corrected to honor the usual disambiguation rules for abbreviated refnames. * jt/refspec-dwim-precedence-fix: remote: make refspec follow the same disambiguation rule as local refs