assertion rewriting fails with 'in' and 'and' operators

[pytestbot]

Originally reported by: Zbigniew Jędrzejewski-Szmek (BitBucket: zbyszek, GitHub: zbyszek)

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Minimal testcase:

  def test_sets():
      assert 1 in {} and 2 in {}

platform linux -- Python 3.3.0 -- pytest-2.1.3dev1

========================================================== ERRORS ==========================================================
_________________________________________ ERROR collecting mdp/test/test_graph.py __________________________________________
../../../../usr/lib/python3.3/site-packages/py-1.4.5-py3.3.egg/py/_path/local.py:529: in pyimport
>           mod = __import__(modname, None, None, ['__doc__'])
../../../../usr/lib/python3.3/site-packages/pytest-2.1.3dev1-py3.3.egg/_pytest/assertion/rewrite.py:136: in find_module
>           co = _rewrite_test(state, fn_pypath)
../../../../usr/lib/python3.3/site-packages/pytest-2.1.3dev1-py3.3.egg/_pytest/assertion/rewrite.py:207: in _rewrite_test
>           co = compile(tree, fn.strpath, "exec")
E           TypeError: non-numeric type in Num
=========================================================== NOTE ===========================================================

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• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/79

[pytestbot]

Original comment by Zbigniew Jędrzejewski-Szmek (BitBucket: zbyszek, GitHub: zbyszek):

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I forgot to mention, that with --assert=plain, it works fine (and the test fails).

[pytestbot]

Original comment by Benjamin Peterson (BitBucket: gutworth, GitHub: gutworth):

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put the explanation generating code in the conditional fail body (fixes #79)

[pytestbot]

Original comment by Zbigniew Jędrzejewski-Szmek (BitBucket: zbyszek, GitHub: zbyszek):

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Thanks!