Traceback entries of a chained exception are filtered in importorskip

[roolebo]

importorskip attempts to perform an import and then raises Skipped exception via skip function which has __tracebackhide__ attribute set to True.

This caused the exception in test_importorskip when I added handling of chained exceptions(#1467):

_______________________ test_importorskip _______________________

monkeypatch = <_pytest.monkeypatch.monkeypatch object at 0x110a1e2e8>

    def test_importorskip(monkeypatch):
        importorskip = pytest.importorskip
        def f():
            importorskip("asdlkj")
        try:
            sys = importorskip("sys")  # noqa
            assert sys == py.std.sys
            #path = pytest.importorskip("os.path")
            #assert path == py.std.os.path
            excinfo = pytest.raises(pytest.skip.Exception, f)
>           path = py.path.local(excinfo.getrepr().reprcrash.path)

testing/test_runner.py:502:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
_pytest/_code/code.py:418: in getrepr
    return fmt.repr_excinfo(self)
_pytest/_code/code.py:609: in repr_excinfo
    reprtraceback = self.repr_traceback(excinfo)
_pytest/_code/code.py:585: in repr_traceback
    last = traceback[-1]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = [], key = -1

    def __getitem__(self, key):
>       val = super(Traceback, self).__getitem__(key)
E       IndexError: list index out of range

_pytest/_code/code.py:289: IndexError

The exception is raised because the traceback entry in the original exception is filtered (because of __tracebackhide__ local variable set to True).

[nicoddemus]

Thanks! Closing as duplicate of #905.