This is for anyone coming in from the Wordpress support forum.

Below is an upgrade patch for upgrading Wordpress 1.5.1 to 1.5.1.3.

I checked the changelogs for 1.5.1.2 and 1.5.1.3 and these are the changed files:

wp-admin/post.php
wp-content/themes/default/header.php
wp-includes/functions-post.php
wp-includes/functions.php
wp-includes/template-functions-category.php
wp-includes/template-functions-general.php
wp-includes/version.php
wp-login.php
xmlrpc.php

There are no database schema changes, so no need to run upgrade.php.

So, first, make a backup, then delete the files listed above:

rm wp-admin/post.php
rm wp-content/themes/default/header.php
rm wp-includes/functions-post.php
rm wp-includes/functions.php
rm wp-includes/template-functions-category.php
rm wp-includes/template-functions-general.php
rm wp-includes/version.php
rm wp-login.php
rm xmlrpc.php

Download my patch file - upgradewordpress1.5.1-1.5.1.3.zip, and upload to your Wordpress root. Then:

unzip upgradewordpress1.5.1-1.5.1.3.zip

You should get:

Archive: upgradewordpress1.5.1-1.5.1.3.zip
inflating: wp-admin/post.php
inflating: wp-content/themes/default/header.php
inflating: wp-includes/functions-post.php
inflating: wp-includes/functions.php
inflating: wp-includes/template-functions-category.php
inflating: wp-includes/template-functions-general.php
inflating: wp-includes/version.php
inflating: wp-login.php
inflating: xmlrpc.php

That’s it. Job done.

Use at your own risk. Don’t come crying to me if it doesn’t work. It worked on the two installs I have.