I've seen this post: http://prdownloads.sourceforge.net/alfresco/alfresco-src-1.2.1.zip?download but I cannot find the upgrade scripts on Sourceforge. Downloaded: alfresco-tomcat-1.2.1.tar.gz and alfresco-src-1.2.1.zip But couldn't find any upgrade instructions (from 1.2)… The ultimate goal is to upgrade to 1.3 (for which prior upgrade to 1.2.1 is "highly recommended").
The upgrade process from 1.2 to 1.2.1 should simply be a matter of stopping the existing server and deploying the new WAR - as the database schema will be auto-updated when you start the server again.
The 1.2.1 to 1.3 upgrade requires that you run the 1.3 database upgrade scripts first - but they only work against 1.2.1 which is why you need to move from 1.2 to 1.2.1 first.