[Distutils] problem with bdist_msi post-install script

["Martin v. Löwis"]

> The only reference to ErrorIcon was commented out by Martin a while
> ago. It was the icon attached to the Error Dialog you.

I'm not quite sure why I commented this out. See whether adding it back
fixes the problem.

The only reason I can see now is that py.ico isn't really an appropriate
error icon, instead, a stop sign or something like that should be used -
I may not have known then (as I don't know now) how to get that into the
MSI file.

Regards,
Martin