Bingo!

$ ./python -m test.regrtest -j 4 test_gdb test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl test_ioctl
[ 1/20] test_ioctl
[ 2/20] test_ioctl
[ 3/20] test_ioctl
[ 4/20] test_ioctl
[ 5/20] test_ioctl
[ 6/20] test_ioctl
[ 7/20] test_ioctl
[ 8/20] test_ioctl
[ 9/20] test_ioctl
test_ioctl skipped -- Neither the process group nor the session are attached to /dev/tty
[10/20] test_ioctl
[11/20/1] test_ioctl
test test_ioctl failed -- Traceback (most recent call last):
  File "/home/serhiy/py/cpython/Lib/test/test_ioctl.py", line 66, in test_ioctl_mutate_2048
    self._check_ioctl_mutate_len(2048)
  File "/home/serhiy/py/cpython/Lib/test/test_ioctl.py", line 54, in _check_ioctl_mutate_len
    self.assertIn(rpgrp, ids)
AssertionError: 14270 not found in (14225, 4030)
[12/20/1] test_ioctl
test_ioctl skipped -- Neither the process group nor the session are attached to /dev/tty
[13/20/1] test_ioctl
[14/20/1] test_ioctl
[15/20/1] test_ioctl
[16/20/1] test_ioctl
[17/20/1] test_ioctl
test_ioctl skipped -- Neither the process group nor the session are attached to /dev/tty
[18/20/1] test_ioctl
[19/20/1] test_ioctl
[20/20/1] test_gdb
16 tests OK.
1 test failed:
    test_ioctl
3 tests skipped:
    test_ioctl test_ioctl test_ioctl