You're right, it's remotely possible that on platforms where /dev/urandom could block, Python startup could therefore also block.  And I'm not proposing we fix that, as so far nobody has reported it as a problem.

This suggests to me that yes I'm talking specifically about the regression on Linux in the 3.5 series.

But honestly it's too late for me to say for sure one way or another.  I need to go to bed.

p.s if we have to slip RC1 by a day or two in order to get this settled, that's okay, but hopefully I can keep final on schedule.