upgrade code (july 25 source version) fails

On upgrading, three of the queries fail:

# Failed: ALTER TABLE {F_Threads} ADD COLUMN `Created_drupal` int(11) NOT NULL default '0' AFTER Created, ADD COLUMN `LastPost_drupal` int(11) NOT NULL default '0' AFTER LastPost, DROP INDEX `ForumIDLastPost`

user warning: Unknown column 'Created_drupal' in 'F_Threads' query

# Failed: UPDATE {F_Threads} SET `Created_drupal`=UNIX_TIMESTAMP(`Created`), `LastPost_drupal`=UNIX_TIMESTAMP(`LastPost`)

user warning: Unknown column 'Created_drupal' in 'field list' query:

# Failed: ALTER TABLE {F_Threads} DROP COLUMN `Created`, DROP COLUMN `LastPost`, CHANGE COLUMN `Created_drupal` `Created` int(11) NOT NULL default '0', CHANGE COLUMN `LastPost_drupal` `LastPost` int(11) NOT NULL default '0', ADD INDEX `Created` (`Created`), ADD INDEX `LastPost` (`LastPost`), ADD INDEX `ForumIDLastPost` (`ForumID`,`LastPost`)

user warning: Can't DROP 'ForumIDLastPost'; check that column/key exists

I've analyzed the problem, and it appears that the cause of the failure is the ', DROP INDEX ...' on the first query. There should be four queries, so that if the index being dropped doesn't exist, the first query won't fail:

ALTER TABLE {F_Threads} ADD COLUMN `Created_drupal` int(11) NOT NULL default '0' AFTER Created, ADD COLUMN `LastPost_drupal` int(11) NOT NULL default '0' AFTER LastPost

DROP INDEX `ForumIDLastPost`

UPDATE {F_Threads} SET `Created_drupal`=UNIX_TIMESTAMP(`Created`), `LastPost_drupal`=UNIX_TIMESTAMP(`LastPost`)

ALTER TABLE {F_Threads} DROP COLUMN `Created`, DROP COLUMN `LastPost`, CHANGE COLUMN `Created_drupal` `Created` int(11) NOT NULL default '0', CHANGE COLUMN `LastPost_drupal` `LastPost` int(11) NOT NULL default '0', ADD INDEX `Created` (`Created`), ADD INDEX `LastPost` (`LastPost`), ADD INDEX `ForumIDLastPost` (`ForumID`,`LastPost`)