rhg: Fall back to Python on --repository with an URL...
rhg: Fall back to Python on --repository with an URL
A low-hanging fruit to improve on this would be to properly parse
and handle `file:` URLs. But other Python-based hg supports
some other URL schemes for features that rhg does not support yet.
Differential Revision:
https://phab.mercurial-scm.org/D10101
