Hmm, these changes look like they revert what @ubernostrum [did for Django 1.4 / 1.5 compatibility](https://github.com/mozilla/kuma/commit/312a88e86a7469c1a99fb81ebf694fb4faad044b), and I don't understand either set of changes. What's the difference between `execute_from_command_line` and `execute_manager`?