getremotechanges: fix incoming support

'hg incoming' causes getremotechanges to be called with revs as a
positional argument, which we were not correctly catching here.

hggit/__init__.py

@@ -157,6 +157,9 @@ except ImportError:
 
 def getremotechanges(orig, ui, repo, other, *args, **opts):
     if isinstance(other, gitrepo.gitrepo):
+        if args:
+            revs = args[0]
+        else:
             revs = opts.get('onlyheads', opts.get('revs'))
         git = GitHandler(repo, ui)
         r, c, cleanup = git.getremotechanges(other, revs)