I tried closing -all- of the handles listed here (the std ones used as
input to _get_handles and the pipe read/write ones returned) on an
OSError during CreateProcess but the problem still occurs for me using
the test code in msg68787.

        (p2cread, p2cwrite,
         c2pread, c2pwrite,
         errread, errwrite) = self._get_handles(stdin, stdout, stderr)

someone with more windows willingness/knowledge/fu should take this one on.