[Pytest-commit] Issue #744: py.test assert rewriting broken with Python 3.5a4+ (pytest-dev/pytest)

[gvanrossum]

New issue 744: py.test assert rewriting broken with Python 3.5a4+
https://bitbucket.org/pytest-dev/pytest/issue/744/pytest-assert-rewriting-broken-with-python

gvanrossum:

I am experiencing a traceback ending thus:
```
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:137: in find_module
    source_stat, co = _rewrite_test(state, fn_pypath)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:278: in _rewrite_test
    rewrite_asserts(tree)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:336: in rewrite_asserts
    AssertionRewriter().run(mod)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:550: in run
    new.extend(self.visit(child))
/usr/local/lib/python3.5/ast.py:245: in visit
    return visitor(node)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:658: in visit_Assert
    top_condition, explanation = self.visit(assert_.test)
/usr/local/lib/python3.5/ast.py:245: in visit
    return visitor(node)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:789: in visit_Compare
    left_res, left_expl = self.visit(comp.left)
/usr/local/lib/python3.5/ast.py:245: in visit
    return visitor(node)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:640: in generic_visit
    return res, self.explanation_param(self.display(res))
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:577: in display
    return self.helper("saferepr", expr)
/usr/local/lib/python3.5/site-packages/_pytest/assertion/rewrite.py:583: in helper
    return ast.Call(attr, list(args), [], None, None)
E   TypeError: Call constructor takes either 0 or 3 positional arguments
```
I get this as soon as I have an assert statement in my test (even `assert True`).