Patched some very obscure bugs

test/scripts/index-assignment-both-bugfix.toy

@@ -0,0 +1,15 @@
+/*
+
+This ensures that when indexing on both sides of an assignment,
+it works correctly.
+
+*/
+
+var a = [1, 2, 3];
+var b = [4, 5, 6];
+
+a[1] = b[1];
+
+assert a == [1, 5, 3], "index assignment both failed";
+
+print "All good";