Platform of "x86 Ubuntu Shared 3.x" buildbot: "Linux-2.6.31.5-linode21-i686-with-debian-lenny-sid little-endian", so a Linux kernel 2.6.31.

It looks common on this buildbot that selector.select(timeout) takes less timeout seconds (without returning any event). "dt+granularity > timeout" test is False and so _run_once() does nothing, a new call is required.

Debug output of test_asyncio on "x86 Ubuntu Shared 3.x" (build 9632, test_asyncio passed):
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[ 75/389] test_asyncio
WARNING: selector.select(timeout=0.09994344785809516907) took dt=0.09897190984338521957 sec (dt-timeout=-0.00097153801470994949)
WARNING: dt+0.00100000000000000002 > timeout? True
WARNING: selector.select(timeout=0.09991932008415460587) took dt=0.09855401515960693359 sec (dt-timeout=-0.00136530492454767227)
WARNING: dt+0.00100000000000000002 > timeout? False
WARNING: selector.select(timeout=0.00097305513918399811) took dt=0.00002539902925491333 sec (dt-timeout=-0.00094765610992908478)
WARNING: dt+0.00100000000000000002 > timeout? True
WARNING: selector.select(timeout=0.49995081406086683273) took dt=0.10032826289534568787 sec (dt-timeout=-0.39962255116552114487)
WARNING: dt+0.00100000000000000002 > timeout? False
WARNING: selector.select(timeout=0.39888287801295518875) took dt=0.39831575006246566772 sec (dt-timeout=-0.00056712795048952103)
WARNING: dt+0.00100000000000000002 > timeout? True
WARNING: selector.select(timeout=None) took dt=0.01029967889189720154 sec
WARNING: selector.select(timeout=None) took dt=0.07110145408660173416 sec
WARNING: selector.select(timeout=None) took dt=0.00214391853660345078 sec
WARNING: selector.select(timeout=None) took dt=0.00361407827585935593 sec
WARNING: selector.select(timeout=0.00991696026176214218) took dt=0.00975166168063879013 sec (dt-timeout=-0.00016529858112335205)
WARNING: dt+0.00100000000000000002 > timeout? True
WARNING: selector.select(timeout=0.49995493795722723007) took dt=0.10188415739685297012 sec (dt-timeout=-0.39807078056037425995)
WARNING: dt+0.00100000000000000002 > timeout? False
WARNING: selector.select(timeout=None) took dt=0.01038167160004377365 sec
WARNING: selector.select(timeout=None) took dt=0.00922694429755210876 sec
WARNING: selector.select(timeout=None) took dt=0.00215751212090253830 sec
WARNING: selector.select(timeout=None) took dt=0.01459381356835365295 sec
WARNING: selector.select(timeout=0.49995700363069772720) took dt=0.10038192663341760635 sec (dt-timeout=-0.39957507699728012085)
WARNING: dt+0.00000100000000000000 > timeout? False
WARNING: selector.select(timeout=None) took dt=0.01037232112139463425 sec
WARNING: selector.select(timeout=None) took dt=0.00168939027935266495 sec
WARNING: selector.select(timeout=None) took dt=0.00139459036290645599 sec
WARNING: selector.select(timeout=None) took dt=0.00180943403393030167 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
WARNING: selector.select(timeout=None) took dt=0.00000000000000000000 sec
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