Test canonical prunable txout format explicitly

src/test/data/script_invalid.json

@@ -39,6 +39,9 @@
 ["1", "RETURN"],
 ["1", "DUP IF RETURN ENDIF"],
 
+["1", "RETURN 'data'", "canonical prunable txout format"],
+["0 IF", "RETURN ENDIF 1", "still prunable because IF/ENDIF can't span scriptSig/scriptPubKey"],
+
 ["0", "VERIFY 1"],
 ["1", "VERIFY"],
 ["1", "VERIFY 0"],

src/test/data/script_valid.json

@@ -34,6 +34,8 @@
 ["1 0", "NOTIF IF 1 ELSE 0 ENDIF ELSE IF 0 ELSE 1 ENDIF ENDIF"],
 ["0 1", "NOTIF IF 1 ELSE 0 ENDIF ELSE IF 0 ELSE 1 ENDIF ENDIF"],
 
+["0", "IF RETURN ENDIF 1", "RETURN only works if executed"],
+
 ["1 1", "VERIFY"],
 
 ["10 0 11 TOALTSTACK DROP FROMALTSTACK", "ADD 21 EQUAL"],