[pypy-dev] __exit__ not called in certain cases

[Hong Minhee]

I reported https://bugs.pypy.org/issue1126 which shows that __exit__
is not called in certain cases when I think it should be.  The code to
reproduce the bug is there. The code works on CPython.

It was closed as invalid saying this is a GC issue, but I don't think
it is.  This is about __exit__, not __del__.  __exit__ should be
always called if __enter__ succeeds.