#15872: Fix 3.3 regression introduced by the new fd-based shutil.rmtree

It caused rmtree to not ignore certain errors when ignore_errors was set.

Patch by Alessandro Moura and Serhiy Storchaka.

diff --cc Lib/shutil.py
Simple merge

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

diff --cc Misc/NEWS
Simple merge