Fix :sigspace fossil on quoting constructs

Author: lizmat

S02-bits.pod

@@ -3844,7 +3844,7 @@ to a different parser.  This can completely change the interpretation
 of any subsequent adverbs as well as the quoted material itself.
 
     q:s//       Q :q :scalar //
-    rx:s//      Q :regex :sigspace //
+    rx:s//      Q :regex :scalar //
 
 Just as C<q[...]> has the short form C<'...'>, and C<qq[...]> has the
 short form C<"...">, the completely quoted C<Q[...]> has a short form