Ok, so for the moment, let's set aside the connection refused messages: 
that may be a case of not cleaning up a socket correctly (which is still 
bad, but not memory corruption).

Of note from the buildbot failure:
Assertion failed: (bp != NULL), function PyObject_Malloc, file 
Objects/obmalloc.c, line 746.
test test_multiprocessing failed -- errors occurred; run in verbose mode 
for details

I don't know enough about obmalloc.c to state if this is a problem with 
it not being multithreaded

Here's another failure (from my own buildbot to boot):

test_multiprocessing
/Users/buildbot/buildarea/trunk.noller-
osx86/build/Lib/multiprocessing/__init__.py:82: ImportWarning: Not 
importing directory '/Users/buildbot/buildarea/trunk.noller-
osx86/build/Modules/_multiprocessing': missing __init__.py
  import _multiprocessing
Fatal Python error: Objects/tupleobject.c:169 object at 0x539d538 has 
negative ref count -606348326
make: *** [buildbottest] Abort trap
program finished with exit code 2