Fix List.ACCEPTS regression

List.ACCEPTS really has to return the list and not boolify too early.
Otherwise my @matches = $foo ~~ m:g/bar/; breaks

src/core/List.pm

@@ -379,7 +379,7 @@ my class List does Iterable does Positional { # declared in BOOTSTRAP
     }
 
     multi method ACCEPTS(List:D: $topic) {
-        return ?self unless nqp::istype($topic, Iterable);
+        return self unless nqp::istype($topic, Iterable);
         my $sseq = self;
         my $tseq = $topic;