Fix duplicated_step.feature in selftest.features.

Fixes issue #122 to the extent that the tests pass again.

It did occur to me that maybe this screws up the conditions of the test itself, and makes it pass 'by default' but unless I'm missing something, I don't think that is the case. A duplicated step is still loaded as a condition. It still throws the expected error. The only change I made to the feature/test is to assert based on `<...>/step1.py` instead of `<...>/step2.py`.