Addition to fix for bug#10974. Fixed spelling.

mysql-test/r/merge.result

@@ -178,9 +178,9 @@ t3	CREATE TABLE `t3` (
 ) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 UNION=(`t1`,`t2`)
 create table t4 (a int not null, b char(10), key(a)) engine=MERGE UNION=(t1,t2);
 select * from t4;
-ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exists
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 alter table t4 add column c int;
-ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exists
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 create database mysqltest;
 create table mysqltest.t6 (a int not null primary key auto_increment, message char(20));
 create table t5 (a int not null, b char(20), key(a)) engine=MERGE UNION=(test.t1,mysqltest.t6);
@@ -775,9 +775,9 @@ DROP TABLE t1, t2;
 CREATE TABLE t1(a INT) ENGINE=MEMORY;
 CREATE TABLE t2(a INT) ENGINE=MERGE UNION=(t1);
 SELECT * FROM t2;
-ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exists
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 DROP TABLE t1, t2;
 CREATE TABLE t2(a INT) ENGINE=MERGE UNION=(t3);
 SELECT * FROM t2;
-ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exists
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 DROP TABLE t2;

sql/share/english/errmsg.txt

@@ -184,7 +184,7 @@ character-set=latin1
 "INSERT DELAYED can't be used with table '%-.64s' because it is locked with LOCK TABLES",
 "Incorrect column name '%-.100s'",
 "The used storage engine can't index column '%-.64s'",
-"Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exists",
+"Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist",
 "Can't write, because of unique constraint, to table '%-.64s'",
 "BLOB/TEXT column '%-.64s' used in key specification without a key length",
 "All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead",