Fix pytest 4.1 compatibilty #12934
Description
The pytest 4.1 removes a number of deprecated features (and deprecates others), see changelog.
In #12931 all tests fail with pytest 4.1, with,
__________________________ test_affinity_propagation ___________________________
self = <pytest_cov.plugin.CovPlugin object at 0x7ffa393f27f0>
item = <Function test_affinity_propagation>
@compat.hookwrapper
def pytest_runtest_call(self, item):
> if (item.get_marker('no_cover')
or 'no_cover' in getattr(item, 'fixturenames', ())):
E AttributeError: 'Function' object has no attribute 'get_marker'
item = <Function test_affinity_propagation>
self = <pytest_cov.plugin.CovPlugin object at 0x7ffa393f27f0>
/home/travis/build/scikit-learn/scikit-learn/testvenv/lib/python3.5/site-packages/pytest_cov/plugin.py:289: AttributeError
this would need more investigation, but it if turns out that we were using a deprecated pytest feature the fix should also be backported to the 0.20.X branch.