Just pulled 64380ee4bbc5 (r88500) and compiled, Python's busted:

Fatal Python error: Py_Initialize: can't initialize sys standard streams
Traceback (most recent call last):
  File "/Users/steffen/usr/opt/py3k/lib/python3.3/io.py", line 60, in <module>
Abort trap

Can you try to identify which revision introduced the issue?

Let me see some minutes.

According to adorable but slow Mercurial:

The first bad revision is:
changeset:   9894:fc8a94cc17a4
branch:      py3k
user:        raymond.hettinger
date:        Tue Feb 22 01:41:50 2011 +0100
summary:     [svn r88490] Issue #11085: Moved collections abstract base classes into a separate module

Hmm.  Note that this problem does *not* occur if i don't install Python but run it in place, e.g. 'cd Lib/test; ../../python.exe -m test -v -uall test_iter' works just perfect.

... and the problem is all gone with 8c2935f180fa/r88525.
So i'm faitful now and close this early alpha-stage problem.
One of the nosy ones may add a nice description, re-open it or so.

(.. should close it, then.)

For the record:

> e.g. 'cd Lib/test; ../../python.exe -m test -v -uall test_iter' works
> just perfect.

You don't need to "cd". Just "./python -m test (etc.)".
See http://docs.python.org/devguide/runtests.html for more information.