--pdb breaks django TestCase db flush/rollback

[asfaltboy]

Added a failing test case in this branch:
https://github.com/asfaltboy/pytest-django/blob/feature/pdb-failure/tests/test_unittest.py#L249

[blueyed]

Please submit it as a PR, so we can discuss it here.

[asfaltboy]

Latest changes in pytest 3.0.2, cause this, discussion in PR #406