hgcia: Handle URL like in notify (
issue2406)
The URL must be composed with baseurl and webroot like in notify
util: make str(url) return file:/// for abs paths again
str(url) was recently changed to return only file:/. However, the
canonical way to represent absolute local paths is file:/// [1], which
is also expected by at least hgsubversion.
Relative paths are returned as file:the/relative/path.
[1] http://en.wikipedia.org/wiki/File_URI_scheme
subrepo: use a safer revision check for hg repos
This avoids a traceback if the expected revision has been stripped.