robustapply and cross-interpreter compatibility

[fijal]

I would like to bring this issue up:

http://code.djangoproject.com/ticket/6857

We attached pypy-compatible version of robustapply.py, which works
under cpython, pypy and jython correctly. I know that robustapply.py
is going away at some point, but this patch is relatively trivial and
actually commiting it would help me to get rid of pypy-compatible
django fork.

Cheers,
fijal