Give error if locked table is used twice in query. This fixes strange error message when doing LOCK TABLES t1 WRITE; INSERT TABLE t1 SELECT * from t1 (Bug #2296)


client/mysqldump.c:
  Better help for flush-logs
mysql-test/r/lock.result:
  Test for LOCK TABLES ; INSERT ... SELECT
mysql-test/t/lock.test:
  Test for LOCK TABLES ; INSERT ... SELECT