These are changes necessary to mailbox.py and its tests so that tests pass (windows platform) on pypy 1.9.0. Files must be explicitly closed on pypy. 

I would like to submit these as a "compatability" issue type, but that category does not exist, so I used "behavior". 

This is the first in a series of a number of such patches, I think there will be about 20.

I see some code changes, but no added tests for those code changes.

msg.fp doesn't exist in Python3.  I'd like to understand those changes better, but I don't know when I'll have the time or if it is worth the effort.

Oh, and the code changes should presumably be applied to Python3 as well (once there are tests), so I've added those versions.  It might be better to have two patches, one for the close of _file, and the other for the msg.fp stuff (since that doesn't exist in Python3).

I'm not sure about the __del__: if pypy's deferred garbage collection is not enough to close self._file, how can a __del__ method help?

Revised patch: changes to mailbox.py were not needed for pypy. Someone did a good job with mailbox.py in stdlib 2.7.3

Now the patch only changes tests. The tests in 3.3 are very different, it seems to me there is little that can be reused there.

Ah, good.  I thought we'd fixed the open/close issues, but I could easily believe we had missed something (especially in Python2).

Since the fp stuff is gone in 3, I'd be OK with just applying this.

What is the next stage in moving this forward? I am new here...

You could get one of the pypy devs that have push rights on cpython to commit it.  If that doesn't happen, then at some point (probably not *too* long from now) I or someone else will commit it.  We have many more patches than we have people with time to commit them, so it sometimes takes a bit.

New changeset 84cd07899baf by Petri Lehtinen in branch '2.7':
#15040: Close files in mailbox tests for PyPy compatibility
http://hg.python.org/cpython/rev/84cd07899baf

Applied, thanks!