Change error message for rejected input.

Author: Thomas G. Lockhart

src/test/regress/expected/boolean.out

@@ -101,8 +101,7 @@ QUERY: INSERT INTO BOOLTBL2 (f1) VALUES ('False'::bool);
 QUERY: INSERT INTO BOOLTBL2 (f1) VALUES ('FALSE'::bool);
 QUERY: INSERT INTO BOOLTBL2 (f1)
    VALUES ('XXX'::bool);
-WARN:Invalid input string 'XXX'
-
+WARN:Bad boolean external representation 'XXX'
 QUERY: SELECT '' AS f_4, BOOLTBL2.*;
 f_4|f1
 ---+--