I haven't seen any such hangs. I've seen one test_asyncio failure on FreeBSD 6.4 3.x, which is the following weirdness.

http://buildbot.python.org/all/builders/x86%20FreeBSD%206.4%203.x/builds/4116/steps/test/logs/stdio

test test_asyncio crashed -- Traceback (most recent call last):
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/test/regrtest.py", line 1276, in runtest_inner
    test_runner()
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/test/test_asyncio/__init__.py", line 31, in test_main
    run_unittest(suite())
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/test/test_asyncio/__init__.py", line 21, in suite
    __import__(mod_name)
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/test/test_asyncio/test_base_events.py", line 10, in <module>
    from asyncio import base_events
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/asyncio/__init__.py", line 13, in <module>
    from .futures import *
  File "/usr/home/db3l/buildarea/3.x.bolen-freebsd/build/Lib/asyncio/futures.py", line 12, in <module>
    from . import events
ImportError: cannot import name 'events'

Sadly there's no more info about this -- does this mean events.py is corrupt? Or is one of the imports in events.py breaking? Then why doesn't it show the failing line?