Fix cit.py when ~/.chrome-infra exists but does not have infra.

R=hinoka@chromium.org, stip@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1457563002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@297583 0039d316-1c4b-4281-b951-d872f2087c98

cit.py

@@ -42,6 +42,9 @@ def need_to_update(branch):
   except OSError:
     return True  # Gclient failed, definitely need to update.
 
+  if not os.path.isdir(INFRA_DIR):
+    return True
+
   local_rev = get_git_rev(INFRA_DIR, 'HEAD')
 
   subprocess.check_call(