a script that fixes anti-GRANT'ness of privilege tables.

It can appear as a result of manual modifications with INSERT/UPDATE/DELETE

This script converts privilege table to the state that could be created
with GRANT commands only (with the exception of the short password)

This is necessary for 5.0

scripts/mysql_prepare_privilege_tables_for_5.sql

+
+use mysql;
+
+--
+-- merging `host` table and `db`
+--
+
+UPDATE IGNORE host SET Host='%' WHERE Host='';
+DELETE FROM host WHERE Host='';
+
+INSERT IGNORE INTO db (User, Host, Select_priv, Insert_priv, Update_priv,
+    Delete_priv, Create_priv, Drop_priv, Grant_priv, References_priv,
+    Index_priv, Alter_priv, Create_tmp_table_priv, Lock_tables_priv)
+  SELECT d.User, h.Host,
+    (d.Select_priv           = 'Y' || h.Select_priv           = 'Y') + 1,
+    (d.Insert_priv           = 'Y' || h.Select_priv           = 'Y') + 1,
+    (d.Update_priv           = 'Y' || h.Update_priv           = 'Y') + 1,
+    (d.Delete_priv           = 'Y' || h.Delete_priv           = 'Y') + 1,
+    (d.Create_priv           = 'Y' || h.Create_priv           = 'Y') + 1,
+    (d.Drop_priv             = 'Y' || h.Drop_priv             = 'Y') + 1,
+    (d.Grant_priv            = 'Y' || h.Grant_priv            = 'Y') + 1,
+    (d.References_priv       = 'Y' || h.References_priv       = 'Y') + 1,
+    (d.Index_priv            = 'Y' || h.Index_priv            = 'Y') + 1,
+    (d.Alter_priv            = 'Y' || h.Alter_priv            = 'Y') + 1,
+    (d.Create_tmp_table_priv = 'Y' || h.Create_tmp_table_priv = 'Y') + 1,
+    (d.Lock_tables_priv      = 'Y' || h.Lock_tables_priv      = 'Y') + 1
+  FROM db d, host h WHERE d.Host = '';
+
+UPDATE IGNORE db SET Host='%' WHERE Host = '';
+DELETE FROM db WHERE Host='';
+
+TRUNCATE TABLE host;
+
+--
+-- Adding missing users to `user` table
+--
+-- note that invalid password causes the user to be skipped during the
+-- load of grand tables (at mysqld startup) thus three following inserts
+-- do not affect anything
+
+INSERT IGNORE user (User, Host, Password) SELECT User, Host, "*" FROM db;
+INSERT IGNORE user (User, Host, Password) SELECT User, Host, "*" FROM tables_priv;
+INSERT IGNORE user (User, Host, Password) SELECT User, Host, "*" FROM columns_priv;
+
+SELECT DISTINCT
+"There are user accounts with the username 'PUBLIC'. In the SQL-1999
+(or later) standard this name is reserved for PUBLIC role and can
+not be used as a valid user name. Consider renaming these accounts before
+upgrading to MySQL-5.0.
+These accounts are:" x
+FROM user WHERE user='PUBLIC';
+SELECT CONCAT(user,'@',host) FROM user WHERE user='PUBLIC';
+