Fix git try. git_try.py imports git_cl.py without calling its main.

Make sure settings is correctly initialized.

TBR=dpranke@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/8745014

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@112222 0039d316-1c4b-4281-b951-d872f2087c98

git_cl.py

@@ -311,6 +311,10 @@ def ShortBranchName(branch):
 class Changelist(object):
   def __init__(self, branchref=None):
     # Poke settings so we get the "configure your server" message if necessary.
+    global settings
+    if not settings:
+      # Happens when git_cl.py is used as a utility library.
+      settings = Settings()
     settings.GetDefaultServerUrl()
     self.branchref = branchref
     if self.branchref: