remote-hg: add remote tests

The logic when working with a local repository is totally different from
the one where we work with a remote repository; we need to pull and push
from it.

All this logic is currently not tested at all, so let's introduce a
variable to force the remote behavior.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/remote-helpers/git-remote-hg

@@ -383,7 +383,7 @@ def get_repo(url, alias):
 
     extensions.loadall(myui)
 
-    if hg.islocal(url):
+    if hg.islocal(url) and not os.environ.get('GIT_REMOTE_HG_TEST_REMOTE'):
         repo = hg.repository(myui, url)
         if not os.path.exists(dirname):
             os.makedirs(dirname)