hg parses -R and --repository CLI arguments "early" in order to know which
local repository to load config from. (Config can then affect whether or how to
The value of of those arguments can be not only a filesystem path, but also an
alias configured in the [paths] section. This part was missing in rhg and this
patch implements that.
The `#if no-rhg` is still not removed completely as those two `[paths]` are read
from `.hg/hgrc` of directory in which the command is running. That will be
implemented in the next patch.