Hi Gareth,
I went another direction, and used a copy of my Moodle 2.3.6 (Build: 20130318) production site to try a test upgrade to Moodle 2.5dev (Build: 20130322)...and it failed. It appears there have been two new fields added to the mdl_folder table that caused the upgrade to fail. I manually added the two new fields with phpMyAdmin, and then the upgrade proceded as expected.
The two new fields are show_expanded and display. I think they were added to give new capability to show sub-folders already expanded when using the Folder Resource.
Later today or tomorrow, after I finish doing my taxes , I am going to start over and do it again, trying with production data that has and does not have the folder table in use to see if it makes a difference in the upgrade process.
Has anyone else running upgrade experiments, noticed this?
AL