Rearrange and re-fudge Bag symmetric difference.

Coming up with a definition of Bag symmetric difference changes the answers we
are looking for. In addition I've moved the corresponding tests from set.t to
bag.t, and fudged them because Rakudo cannot handle them properly yet.  (ab5tract++ and I are working on making them work.)

S03-operators/bag.t

@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 109;
+plan 117;
 
 sub showkv($x) {
     $x.keys.sort.map({ $^k ~ ':' ~ $x{$k} }).join(' ')
@@ -58,6 +58,21 @@ isa_ok ($s (&) $kb), Bag, "... and it's actually a Bag";
 is showkv($kb (&) <glad green blood>), "blood:1", "BagHash intersection with array of strings works (texas)";
 isa_ok ($kb (&) <glad green blood>), Bag, "... and it's actually a Bag";
 
+# symmetric difference
+
+#?rakudo 8 todo 'Rakudo is getting this wrong at the moment, fix coming soon'
+is showkv($s (^) $b), showkv($s (|) $b), "Bag symmetric difference with Set is correct";
+isa_ok ($s (^) $b), Bag, "... and it's actually a Bag";
+is showkv($b (^) $s), showkv($s (|) $b), "Set symmetric difference with Bag is correct";
+isa_ok ($b (^) $s), Bag, "... and it's actually a Bag";
+
+#?niecza todo "Test is wrong, implementation is wrong"
+is showkv($s (^) $kb), showkv(($s (|) $kb) (-) ($s (&) $kb)), "BagHash subtracted from Set is correct";
+isa_ok ($s (^) $kb), Bag, "... and it's actually a Bag";
+#?niecza todo "Test is wrong, implementation is wrong"
+is showkv($kb (^) $s), showkv(($s (|) $kb) (-) ($s (&) $kb)), "Set subtracted from BagHash is correct";
+isa_ok ($kb (^) $s), Bag, "... and it's actually a Bag";
+
 # Bag multiplication
 
 is showkv($s ⊍ $s), "blood:1 love:1", "Bag multiplication with itself yields self squared";

S03-operators/set.t

@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 296;
+plan 288;
 
 sub showset($s) { $s.keys.sort.join(' ') }
 sub showkv($x) { $x.keys.sort.map({ $^k ~ ':' ~ $x{$k} }).join(' ') }
@@ -126,19 +126,7 @@ isa_ok ($s (^) $ks), Set, "... and it's actually a Set";
 is showset($ks (^) $s), showset(set <is isn't your day>), "Set symmetric difference with SetHash is correct";
 isa_ok ($ks (^) $s), Set, "... and it's actually a Set";
 
-is showset($s (^) $b), showset($s (|) $b), "Bag symmetric difference with Set is correct";
-isa_ok ($s (^) $b), Set, "... and it's actually a Set";
-is showset($b (^) $s), showset($s (|) $b), "Set symmetric difference with Bag is correct";
-isa_ok ($b (^) $s), Set, "... and it's actually a Set";
-
-#?niecza todo "Test is wrong, implementation is wrong"
-#?rakudo todo 'huh?'
-is showset($s (^) $kb), showset(($s (|) $kb) (-) set <your>), "BagHash subtracted from Set is correct";
-isa_ok ($s (^) $kb), Set, "... and it's actually a Set";
-#?niecza todo "Test is wrong, implementation is wrong"
-#?rakudo todo 'huh?'
-is showset($kb (^) $s), showset(($s (|) $kb) (-) set <your>), "Set subtracted from BagHash is correct";
-isa_ok ($kb (^) $s), Set, "... and it's actually a Set";
+# symmetric difference with Bag moved to bag.t
 
 # is subset of