provide error fixture applied to the same func

[ApaDoctor]

Ref #2334

[RonnyPfannschmidt]

i am fairly certain that unless we raise a deprecation warning for one feature iteration at least its going to break people quite a bit unexpectedly

@nicoddemus i'd like your opinion on that

[RonnyPfannschmidt]

oh, i just cross-checked the prior pr in #2814 - since @nicoddemus suggested the error it may be fine

[RonnyPfannschmidt]

for completeness please add a unittest

something like

def test_fixture_disallow_twice():
   with pytest.raises(ValueError):
       @pytest.fixture
       @pytest.fixture
       def foo():
          pass

[nicoddemus]

Thanks @ApaDoctor! Agree that we should add a test for it.

I updated the changelog a bit, hope you don't mind (I gotta say that I just love being able to quickly edit files directly while reviewing a PR 😄 )

[coveralls]

Coverage increased (+0.05%) to 92.773% when pulling 132fb61 on ApaDoctor:disable-repeated-fixture into 3318e53 on pytest-dev:features.

[RonnyPfannschmidt]

@nicoddemus thanks for finishing it up