Well, it turns out I was totally wrong about the 11700 dependency.  I misread the errors that were produced by the test suite.  Even after fixing 11700 they are still there: the tests are reading from the closed files.  So something changed in the logic between 2.7 and 3.x.  It is possible that this is related to the addition of context manager support, and is almost certainly related to the general cleanup of unclosed files that was done after Antoine's ResourceWarning patch.

Filip, do you want to investigate this?  We always have the option of ignoring the problem in 2.7, but since you reported it against 2.7 I'm guessing you'd like to see it fixed there.

I'm attaching a version of the patch that applies cleanly to 2.7 tip.