Fix duplicated_step.feature

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`.