I use Linux (Ubuntu GNOME, 17.04, 64-bit) on all my computers, and I use  ZFS for the /home partition.  While releasing 3.4.7rc1 and 3.5.4rc1, I encountered this test failure:

% ./python -m test test_resource
0:00:00 load avg: 0.40 [1/1] test_resource
test test_resource failed -- Traceback (most recent call last):
  File "/home/larry/src/python/releases/test35/Lib/test/test_resource.py", line 55, in test_fsize_enforced
    f.write(b"X" * 1024)
OSError: [Errno 27] File too large

1 test failed:
    test_resource
Tests result: FAILURE

If I run this test on another filesystem (e.g. ext4), with the exact same source tree, the test passes.  I also didn't see this failure when releasing 3.4.6 and 3.5.3 earlier this year.

This is probably caused by new behavior in an recent update to ZFS.  So I'm not sure if this is a ZFS bug, and if it is I don't know whether or not we should work around it.  But it's hard to imagine ZFS is behaving correctly here.

I've confirmed that this happens in all four branches tagged (3.4 through 3.7).  Since it causes test failures, I'm willing to consider accepting a PR for 3.4 and 3.5.

Serhiy, I've tagged you since you were the last person to touch resource.getrlimit and resource.setrlimit.  Are you interested / willing to look at this bug?  Do you have a computer with a ZFS filesystem you can use to run experiments?