Ok, I found the cause: it's in https://github.com/mozilla/zamboni/blob/master/lib/settings_base.py#L456 : that's a **regex**, which means ignore everything that matches "mkt" with 0 or more slashes.

I thought I'd then correct this to ```mkt/.*``` but it then executes tests like:

```
#26 test_decimal (zamboni.mkt.api.tests.test_serializer.TestSerializer) ... ok
#27 test_deserialization_error (zamboni.mkt.api.tests.test_serializer.TestSerializer) ... ok
#28 test_from_url (zamboni.mkt.api.tests.test_serializer.TestSerializer) ... ok
#29 test_json (zamboni.mkt.api.tests.test_serializer.TestSerializer) ... ok
#30 test_url (zamboni.mkt.api.tests.test_serializer.TestSerializer) ... ok
```