This is the expected behavior on OSX. Apple has a pretty odd interpretation of the standards wrt getgroups and setgroups behavior. 

This behavior is not a bug in python

Sent from my iPhone

On 11 nov. 2010, at 22:17, Stephen Hansen <report@bugs.python.org> wrote:

> 
> Stephen Hansen <me+python@ixokai.io> added the comment:
> 
> This test is failing again, and IIUC, largely due to the same sort of issues: http://www.python.org/dev/buildbot/all/builders/AMD64%20Leopard%203.1/builds/65
> 
> I was able to track down what exactly caused it to fail in this case on my box, though. Whatever "posix.getgroups()" ends up calling, appears to be tied to the current users login -- or at least, doesn't get updated when new groups are added to the user.
> 
> This failure happened because at some point after the buildbot was up and running, I added a new user to the machine (totally unconnected to the existing buildbot runner): this caused a new group to be added to the buildbot runner's user.
> 
> "id -G" starts returning that group immediately, but "posix.getgroups()" returns the same list as it had before. I was able to further reproduce it in Terminal, by having a console open, and compiling 3.1 there then adding a user, and running the test. It fails. Opening up a new terminal window, running the test-- and it succeeds. The original console continues to fail.
> 
> ----------
> nosy: +ixokai
> versions: +Python 3.1, Python 3.2
> 
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue7900>
> _______________________________________