context: drop support for changeid='' (API) Since the previous commit, there seem to be no users who pass '' to repo.__getitem__, so let's drop support for it. It may seem like a small cost to keep support for it, but I've spent time being confused by it twice already. Differential Revision: https://phab.mercurial-scm.org/D3021

subrepo: use repo['.'] instead of repo[''] The "state" value (a revision) passed to abstractsubrepo.phase() can be '' to represent the currently checked out revisions. Let's convert that to the more common '.'. I think this is the last of use of repo['.'] in core. Differential Revision: https://phab.mercurial-scm.org/D3019

children: use repo['.'] instead of repo[''] Differential Revision: https://phab.mercurial-scm.org/D3020

revset: drop support for '' as alias for '.' Not marked BC because I think support for using '' on the CLI was there by accident, and we don't seem to have documented it. Differential Revision: https://phab.mercurial-scm.org/D3018

tests: add test showing current parse of empty string symbol in revset We support e.g. parents(""), but I think that's by accident and I'll change it soon. Differential Revision: https://phab.mercurial-scm.org/D3017

clone: rename "rev" to "revs" since there can be many It was a little tricky in hg.clone(), since there was a local "revs" variable defined there, but "rev" was never used after "revs", so I just overwrote it. Note that clonewithshare() should also have its "rev" argument renamed to "revs", but I'll leave that to someone else. Differential Revision: https://phab.mercurial-scm.org/D3016

parseurl: consistently call second output "branches" Differential Revision: https://phab.mercurial-scm.org/D3015