Merge mysql.com:/home/svoj/devel/mysql/BUG29957/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG29957/mysql-5.1-engines


storage/myisam/mi_extra.c:
  Auto merged
mysql-test/r/alter_table.result:
  Manual merge
mysql-test/t/alter_table.test:
  Manual merge

mysql-test/r/alter_table.result

@@ -1172,3 +1172,15 @@ SELECT * FROM t1;
 f1	f2	f3
 1	2	NULL
 DROP TABLE t1;
+create table t1 (c char(10) default "Two");
+lock table t1 write;
+insert into t1 values ();
+alter table t1 modify c char(10) default "Three";
+unlock tables;
+select * from t1;
+c
+Two
+check table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+drop table t1;

mysql-test/t/alter_table.test

@@ -902,3 +902,15 @@ SELECT * FROM t1;
 ALTER TABLE t1 MODIFY COLUMN f3 INT AFTER f2;
 SELECT * FROM t1;
 DROP TABLE t1;
+
+#
+# BUG#29957 - alter_table.test fails
+#
+create table t1 (c char(10) default "Two");
+lock table t1 write;
+insert into t1 values ();
+alter table t1 modify c char(10) default "Three";
+unlock tables;
+select * from t1;
+check table t1;
+drop table t1;

storage/myisam/mi_extra.c

@@ -258,7 +258,7 @@ int mi_extra(MI_INFO *info, enum ha_extra_function function, void *extra_arg)
   case HA_EXTRA_PREPARE_FOR_DELETE:
     pthread_mutex_lock(&THR_LOCK_myisam);
     share->last_version= 0L;			/* Impossible version */
-#ifdef __WIN__
+#ifdef __WIN__REMOVE_OBSOLETE_WORKAROUND
     /* Close the isam and data files as Win32 can't drop an open table */
     pthread_mutex_lock(&share->intern_lock);
     if (flush_key_blocks(share->key_cache, share->kfile,