We use to update the internal backup version and release on majors. While it's not used along the process, that information is included on each backup and has helped in the past to detect inconsistencies caused by codebase partially updated and other problems.

Since Moodle 2.4 we are checking version & release with the CI versions checker so this is a task that we should perform always immediately after a major release (hence has been included in https://docs.moodle.org/dev/Release_process#Packaging).

Summary:

1) Both in the new stable branch and in master (file backup/backup.class.php):

• VERSION must match main $version (8 digits).
• RELEASE must match main $release (X.Y format).
  (provide all the needed changes to achieve this)

Side note: this is one of the allowed differences between the just created branch and master over the on-sync period.