[git_cl] Fix typo

Bug: b/351024645
Change-Id: I4a93abd223b8539e0e58d54d8f9d6937ae3bb111
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5698747
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
Commit-Queue: Allen Li <ayatane@chromium.org>

git_cl.py

@@ -3765,7 +3765,7 @@ class GitAuthConfigChanger(object):
             self._set_config(sso_key, None, modify_all=True)
         elif self._mode == GitConfigMode.NEW_AUTH_SSO:
             self._set_config('protocol.sso.allow', 'always')
-            self._set_config(sso_key, base_url, modify_all=True)
+            self._set_config(sso_key, self._base_url, modify_all=True)
         elif self._mode == GitConfigMode.OLD_AUTH:
             self._set_config('protocol.sso.allow', None)
             self._set_config(sso_key, None, modify_all=True)