RE: virtual timers and System.system

[Simon Marlow]

> I don't get it - execve() and friends are supposed to reset 
> all the signal
> handlers back to the default state, aren't they?  And I can't seem to
> construct an example to demonstrate the problem.

Ah, I get it finally :)  It's the itimer, not the signal handler that's
causing the problem.

I'll commit Hannah's fix.

Cheers,
        Simon