Bug#15522 - create ... select and with merge tables

Added test case.
The fix for Bug#20662 does also fix this one.

mysql-test/r/merge.result

@@ -876,4 +876,9 @@ CHECK TABLE tm1;
 Table	Op	Msg_type	Msg_text
 test.tm1	check	status	OK
 DROP TABLE tm1, t1, t2;
+CREATE TABLE t1(c1 INT);
+CREATE TABLE t2 (c1 INT) ENGINE=MERGE UNION=(t1) INSERT_METHOD=FIRST;
+CREATE TABLE IF NOT EXISTS t1 SELECT * FROM t2;
+ERROR HY000: You can't specify target table 't1' for update in FROM clause
+DROP TABLE t1, t2;
 End of 5.0 tests

mysql-test/t/merge.test

@@ -507,4 +507,18 @@ SELECT * FROM tm1;
 CHECK TABLE tm1;
 DROP TABLE tm1, t1, t2;
 
+#
+# Bug#15522 - create ... select and with merge tables
+#
+# This was fixed together with Bug#20662 (Infinite loop in CREATE TABLE
+# IF NOT EXISTS ... SELECT with locked tables).
+# The new behavior for MERGE tables is consistent with the
+# CREATE TABLE SELECT behavior for ordinary tables.
+#
+CREATE TABLE t1(c1 INT);
+CREATE TABLE t2 (c1 INT) ENGINE=MERGE UNION=(t1) INSERT_METHOD=FIRST;
+--error ER_UPDATE_TABLE_USED
+CREATE TABLE IF NOT EXISTS t1 SELECT * FROM t2;
+DROP TABLE t1, t2;
+
 --echo End of 5.0 tests