Initializes correctly 'url'.

R=evan@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7129059

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@88697 0039d316-1c4b-4281-b951-d872f2087c98

git_cl.py

@@ -227,6 +227,7 @@ class Settings(object):
       # The -100 is an arbitrary limit so we don't search forever.
       cmd = ['git', 'log', '-100', '--pretty=medium']
       proc = Popen(cmd, stdout=subprocess.PIPE)
+      url = None
       for line in proc.stdout:
         match = git_svn_re.match(line)
         if match: