Fix 0722ee8

Hey,

first of all: many thanks for your trust adding me as a developer! I hope I can be of some use.

I'm afraid commit 0722ee8 breaks some tests in `cpymadtest.test_model_locator` (order matters). It might be a little overkill but when patching this I decided to use the MRO used by python>=2.3. Probably this will not be of much use, but it doesn't hurt neither.
I would recommend you to use pull requests to merge your branches into master as well, so I could review the changes and help avoid errors.

Best regards,

Thomas