I'm not sure where should I report this. I wasn't able to install the latest version of subsites until I added a new column to the Group table (ALTER TABLE `Group` ADD `AccessAllSubsites` TINYINT NOT NULL DEFAULT '1'). A bug, I guess?
Perhaps try the latest 2.4 branch daily build and latest subsites. Run /dev/build and see if you still get the error.
If you do all bugs should be reported to the open source bug tracker - http://open.silverstripe.org/
I will check the trunk version of ss2.4 as soon as I have a good testing environment set up. I always use dev/build and flash=1 though.