Seems to be okay at least with Python 3.6 "test" version - but maybe there is better way to call these tests - just to be sure the one needed is not being skipped.

On AIX 5.3 TL7 SP0:

root@x064:[/data/prj/aixtools/python/python-3.6.0.162/Lib/test]../../python test_subprocess.py
ssss...........................................s.......................................................s.....s.........s...............................................................s.....s.........s.........................................sssssssssssss
----------------------------------------------------------------------
Ran 254 tests in 113.796s

OK (skipped=24)

On AIX 6.1 TL9 SP4:

michael@x071:[/data/prj/aixtools/python/python-3.6.0.162/Lib/test]../../python test_subprocess.py
ssss...........................................s.......................................................s.....s.........s...............................................................s.....s.........s.........................................sssssssssssss
----------------------------------------------------------------------
Ran 254 tests in 126.684s

OK (skipped=24)
michael@x071:[/data/prj/aixtools/python/python-3.6.0.162/Lib/test]

Please note that GNU libiconv is used by default (version 1.14) rather than IBM iconv.

This may be the key issue (will test 11190 as well)