Remove unnecessary branch in .truncate
Remove unnecessary branch in .truncate

This fixes the difference between `True.truncate` (which returns True)
and `False.truncate` (which returned 0) so they both return self.

tony-o/rakudo,labster/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,tony-o/rakudo,MasterDuke17/rakudo,salortiz/rakudo,labster/rakudo,MasterDuke17/rakudo,salortiz/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tbrowder/rakudo,tbrowder/rakudo,salortiz/rakudo,MasterDuke17/rakudo,tony-o/rakudo,rakudo/rakudo,rakudo/rakudo,tbrowder/rakudo,tony-o/rakudo,salortiz/rakudo,tony-o/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,tony-o/rakudo,MasterDuke17/rakudo,salortiz/rakudo,rakudo/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,labster/rakudo