Fix test by ignoring the failed Proc
Fix test by ignoring the failed Proc

The test is trying to check if rapid-killing a Proc doesn't hang, but
while doing so it awaits the result in sink context. Of course, a
killed Proc should complain loudly, but it didn't do that in the past
because of a bug in Rakudo.

Resolves rakudo/rakudo#3271.

dogbert17/roast,perl6/roast,dogbert17/roast