#32 Rewrite `except` codegen to avoid crashing pypy.
#32 Rewrite `except` codegen to avoid crashing pypy.

Looks like it doesn't handle a None in END_FINALLY. Hopefully, this
does not break anything on CPython. In theory, it should not, as
CPython 3.4+ appears to skip over END_FINALLY in the non-exceptional
case.

pyos/dg