remote-hg: trivial cleanup

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-hg: use a shared repository store

This way we don't have to have duplicated Mercurial objects.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Merge branch 'fc/remote-old/hg' into fc/master