Comment 4 for bug 463321

[1]
         @param code_name: The code-name of the release to upgrade to.
+ @param allow_third_party: Whether to enable non-official APT repo.
+ @param debug: Whether to turn on debug level logging.
+ @param code_name: The code-name of the release to upgrade to.

The docstring for code_name is duplicated.

[2]
+ def cleanup(ignored):
+ os.environ = env_backup
+ return ignored
+
+ deferred.addBoth(cleanup)

I think you don't need that as you're using EnvironSaverHelper.

+1!