Bug #12917164 DROP USER CAN'T DROP USERS WITH LEGACY

    UPPER CASE HOST NAME ANYMORE

Description:
It is not possible to drop users with host names with upper case
letters in them. i.e DROP USER 'root'@'Tmp_Host_Name'; is failing
with error.

Analysis: Since the fix 11748570 we came up with lower case hostnames
as standard. But in the current bug the hostname is created by
mysql_install_db script is still having upper case hostnames. 
So, if we have the hostname with upper case letters like(Tmp_Host_Name)
then we will have as it is stored in the mysql.user table. 
In this case if use "'DROP USER 'root'@'Tmp_Host_Name';" it gives 
error because we do compare with the lower case of hostname since the 
11748570 fix.

Fix: We need to convert the hostname to lower case before storing into 
the mysql.user table when we run the mysql_install_db script.

scripts/mysql_system_tables_data.sql

@@ -25,8 +25,7 @@
 -- Get the hostname, if the hostname has any wildcard character like "_" or "%" 
 -- add escape character in front of wildcard character to convert "_" or "%" to
 -- a plain character
-SET @get_hostname= @@hostname;
-SELECT REPLACE((SELECT REPLACE(@get_hostname,'_','\_')),'%','\%') INTO @current_hostname;
+SELECT LOWER( REPLACE((SELECT REPLACE(@@hostname,'_','\_')),'%','\%') )INTO @current_hostname;
 
 
 -- Fill "db" table with default grants for anyone to
@@ -42,9 +41,9 @@ DROP TABLE tmp_db;
 -- from local machine if "user" table didn't exist before
 CREATE TEMPORARY TABLE tmp_user LIKE user;
 INSERT INTO tmp_user VALUES ('localhost','root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0);
-REPLACE INTO tmp_user SELECT @current_hostname,'root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0 FROM dual WHERE LOWER( @current_hostname) != 'localhost';
+REPLACE INTO tmp_user SELECT @current_hostname,'root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0 FROM dual WHERE @current_hostname != 'localhost';
 REPLACE INTO tmp_user VALUES ('127.0.0.1','root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0);
 INSERT INTO tmp_user (host,user) VALUES ('localhost','');
-INSERT INTO tmp_user (host,user) SELECT @current_hostname,'' FROM dual WHERE LOWER(@current_hostname ) != 'localhost';
+INSERT INTO tmp_user (host,user) SELECT @current_hostname,'' FROM dual WHERE @current_hostname != 'localhost';
 INSERT INTO user SELECT * FROM tmp_user WHERE @had_user_table=0;
 DROP TABLE tmp_user;

scripts/mysql_system_tables_fix.sql

@@ -601,6 +601,9 @@ ALTER TABLE db MODIFY Trigger_priv enum('N','Y') COLLATE utf8_general_ci DEFAULT
 
 UPDATE user SET Trigger_priv=Super_priv WHERE @hadTriggerPriv = 0;
 
+# Convering the host name to lower case for existing users
+UPDATE user SET host=LOWER( host ) WHERE LOWER( host ) <> host;
+
 # Activate the new, possible modified privilege tables
 # This should not be needed, but gives us some extra testing that the above
 # changes was correct