There is a similar (but different?) issue on Windows XP. I tried to fix it with the 4 last commits.

The test uses a busy loop. The scheduled handle is called after 0.100 - granularity. The granularity is usually 15.6 ms on Windows, so the expected mimiumum is around 0.084 (not 0.090). Attached patch test_base_events.patch uses the granularity to test the minimum. The check on the maximum should maybe be removed because of our slow buildbots.

http://buildbot.python.org/all/builders/x86%20XP-4%203.x/builds/10071/steps/test/logs/stdio

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FAIL: test_time_and_call_at (test.test_asyncio.test_base_events.BaseEventLoopTests)
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Traceback (most recent call last):
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows\build\lib\test\test_asyncio\test_base_events.py", line 124, in test_time_and_call_at
    self.assertTrue(0.09 <= t1-t0 <= 0.9, t1-t0)
AssertionError: False is not true : 0.08999999985098839