The GPL repository field not appearing when adding a new repository

The GPL repo entry is not present on the UI on the Versions page when you add a new OS.
This is an Ambari 2.6 with HDP-2.6.5.0. On Ambari 2.7 there is no such issue.

• Install Ambari and accept GPL license.
• Install a HDP version e.g. with http://s3.amazonaws.com/dev.hortonworks.com/HDP/centos6/2.x/BUILDS/2.6.5.0-292/HDP-2.6.5.0-292.xml
• Go to "Stacks and Versions/Versions/Manage Versions/".
• On the "Versions" page select the link of the version (HDP-2.6.5.0)
• On the "Versions / HDP-2.6.5.0" page Add an OS that is not in the VDF file
• The input text box for "HDP-2.6-GPL" repo is missing.

The issue is also present on the "Versions / Register Version" page:

• Go to "Stacks and Versions/Versions/Manage Versions/Register Version".
• The latest stack version is HDP-2.6.5.1100.
• Add "redhat6" OS. This OS is not described in the VDF file.
• The input text box for "HDP-2.6-GPL" repo is missing.