UT Drupal Kit 3.15.1 is an interim release outside of the normal bi-monthly maintenance release cycle. This release fixes an issue introduced in the 3.15.0 release which triggered an error when running the Drupal installer through the admin UI. There are no other changes in this release.
For full details of all issues included in this release, please refer to the changelog on the release notes, which links to the corresponding GitHub issues.