Fixed bug in UPDATE .. ORDER BY

Docs/manual.texi:
  Changelog
mysql-test/r/update.result:
  Test found bug in UPDATE .. ORDER BY
mysql-test/t/update.test:
  Test found bug in UPDATE .. ORDER BY

Docs/manual.texi

@@ -46491,6 +46491,8 @@ Our TODO section contains what we plan to have in 4.0. @xref{TODO MySQL 4.0}.
 
 @itemize @bullet
 @item
+Fixed core dump bug in @code{UPDATE ... ORDER BY }.
+@item
 Changed @code{INSERT INTO .. SELECT} to by default stop on errors.
 @item
 Ignore @code{DATA DIRECTORY} and @code{INDEX DIRECTORY} directives on windows.

mysql-test/r/update.result

@@ -102,3 +102,13 @@ select status from t1;
 status
 1
 drop table t1;
+create table t1 (a int not null, b int not null);
+insert into t1 values (1,1),(1,2),(1,3);
+update t1 set b=4 where a=1 order by b asc limit 1;
+update t1 set b=4 where a=1 order by b desc limit 1;
+select * from t1;
+a	b
+1	4
+1	4
+1	2
+drop table t1;

mysql-test/t/update.test

@@ -76,3 +76,14 @@ alter table t1 change lfdnr lfdnr int(10) unsigned default 0 not null auto_incre
 update t1 set status=1 where type='Open';
 select status from t1;
 drop table t1;
+
+#
+# Test of ORDER BY
+#
+
+create table t1 (a int not null, b int not null);
+insert into t1 values (1,1),(1,2),(1,3);
+update t1 set b=4 where a=1 order by b asc limit 1;
+update t1 set b=4 where a=1 order by b desc limit 1;
+select * from t1;
+drop table t1;

sql/sql_update.cc

@@ -148,7 +148,7 @@ int mysql_update(THD *thd,
     used_key_is_modified=check_if_key_used(table, used_index, fields);
   else
     used_key_is_modified=0;
-  if (used_key_is_modified)
+  if (used_key_is_modified || order)
   {
     /*
     ** We can't update table directly;  We must first search after all

sql/sql_yacc.yy

@@ -2305,10 +2305,6 @@ values:
 
 update:
 	UPDATE_SYM opt_low_priority opt_ignore table_name
-        SET update_list 
-        where_clause 
-        opt_order_clause
-        delete_limit_clause
 	{ 
 	  LEX *lex=Lex;
           lex->sql_command = SQLCOM_UPDATE;
@@ -2316,6 +2312,10 @@ update:
           lex->select->order_list.first=0;
           lex->select->order_list.next= (byte**) &lex->select->order_list.first;
         }
+        SET update_list 
+        where_clause 
+        opt_order_clause
+        delete_limit_clause
 
 update_list:
 	update_list ',' simple_ident equal expr