Victor Stinner wrote:
> Is it a virtual machine or a physical machine? Was your Windows busy?
> Did you run tests in parallel?

Physical, not really other than the tests, and I ran with -j0 (on a machine with 2 single core CPUs).

I'm not sure what I think of the TEST_SLEEP/TEST_SHORT_SLEEP scheme, but I do like the idea behind support.check_time_delta.  I've come up with a couple of alternative ideas (which may or may not actually be worth anything :) in the same vein as the TEST_SLEEP constants:

1) define a support.sleep function that multiplies the value given by some definable constant (default of 1) before passing the value to time.sleep.
2) define a support.sleep_until function, which would sleep for a given interval repeatedly until some condition is satisfied or a timeout is reached.