Merge branch 'js/remote-rename-with-half-configured-remote'

With anticipatory tweaking for remotes defined in ~/.gitconfig (e.g. "remote.origin.prune" set to true, even though there may or may not actually be "origin" remote defined in a particular Git repository), "git remote rename" and other commands misinterpreted and behaved as if such a non-existing remote actually existed. * js/remote-rename-with-half-configured-remote: remote rename: more carefully determine whether a remote is configured remote rename: demonstrate a bogus "remote exists" bug