WriteFile() segfaults...

[Tom Watson]

Over the weekend I seem to have triggered a number of segfaults while
writing tests by sending 0 as the optional bytes written parameter;

   WriteFile(handle, buffer, sizeof(buffer), 0, NULL);

Test patch/runs on testbot here:
https://testbot.winehq.org/JobDetails.pl?Key=36430

I download the resulting .exe and ran it against current git source locally
and it works fine.

Is this a known issue? Something going on with testbot? Something I'm doing
wrong? Or does it require some more investigation?

Cheers.