Strip url trailing backslash.

It's annoying to have it crash much later in a member function call when a
trailing backslash is provided.

R=dpranke@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/8056016

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@103058 0039d316-1c4b-4281-b951-d872f2087c98

rietveld.py

@@ -42,7 +42,7 @@ upload.logging.setLevel(logging.WARNING)  # pylint: disable=E1103
 class Rietveld(object):
   """Accesses rietveld."""
   def __init__(self, url, email, password, extra_headers=None):
-    self.url = url
+    self.url = url.rstrip('/')
     # TODO(maruel): It's not awesome but maybe necessary to retrieve the value.
     # It happens when the presubmit check is ran out of process, the cookie
     # needed to be recreated from the credentials. Instead, it should pass the