calling system gives exception, waitForProcess

[Neil Mitchell]

I have a fix for it now, thanks to dons. I just wrap system in
Control.Exception.catch and it doesn't crash. dons also said that this
has been fixed in head

dons:
 > waitForProcess started raising exceptions if the processed
> had already termianted (I think) in 6.4.1 and the head. It's
> been fixed in the head.

Thanks

Neil