#17479: merge with 3.3.

diff --cc Lib/test/test_io.py
Simple merge

diff --cc Misc/NEWS
index 94843f039e528bba3e70d1dca210abce30c035ea,9a0c9ddb53e15bcdb443b110296dc0ceea3eab84..aaeafc9f86390c513574a79b98a725b3e494345d
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -1033,8 -714,9 +1033,11 @@@ Test
  
  - Issue #15539: Added regression tests for Tools/scripts/pindent.py.
  
 +- Issue #16836: Enable IPv6 support even if IPv6 is disabled on the build host.
 +
+ - Issue #17479: test_io now works with unittest test discovery.
+   Patch by Zachary Ware.
+ 
  - Issue #17066: test_robotparser now works with unittest test discovery.
    Patch by Zachary Ware.