Merge mysql.com:/home/ram/work/b31615/b31615.5.0

into  mysql.com:/home/ram/work/b31615/b31615.5.1

mysql-test/r/ctype_ucs.result

@@ -811,6 +811,14 @@ quote(name)
 ????????
 ????????????????
 drop table bug20536;
+set names ucs2;
+ERROR 42000: Variable 'character_set_client' can't be set to the value of 'ucs2'
+set names ucs2 collate ucs2_bin;
+ERROR 42000: Variable 'character_set_client' can't be set to the value of 'ucs2'
+set character_set_client= ucs2;
+ERROR 42000: Variable 'character_set_client' can't be set to the value of 'ucs2'
+set character_set_client= concat('ucs', substr('2', 1));
+ERROR 42000: Variable 'character_set_client' can't be set to the value of 'ucs2'
 End of 4.1 tests
 CREATE TABLE t1 (a varchar(64) character set ucs2, b decimal(10,3));
 INSERT INTO t1 VALUES ("1.1", 0), ("2.1", 0);

mysql-test/t/ctype_ucs.test

@@ -547,6 +547,18 @@ select quote(name) from bug20536;
 
 drop table bug20536;
 
+#
+# Bug #31615: crash after set names ucs2 collate xxx
+#
+--error 1231
+set names ucs2;
+--error 1231
+set names ucs2 collate ucs2_bin;
+--error 1231
+set character_set_client= ucs2;
+--error 1231
+set character_set_client= concat('ucs', substr('2', 1));
+
 --echo End of 4.1 tests
 
 #