Fix the permission denied errors on Windows.

This is a fix for the permission denied error observed on windows buildbots.

Tests result: FAILURE then FAILURE
test test_urllibnet failed -- Traceback (most recent call last):
  File "D:\cygwin\home\db3l\buildarea\2.7.bolen-windows7\build\lib\test\test_urllibnet.py", line 232, in test_multiple_ftp_retrieves
    "multiple times.\n Error message was : %s" % e)
AssertionError: Failed FTP retrieve while accessing ftp url multiple times.
 Error message was : [Errno 13] Permission denied: 'd:\\temp\\tmpiuquqa'
Example failure:

https://buildbot.python.org/all/#/builders/209/builds/4

https://bugs.python.org/issue27973