Using the 'Discover' permission for anonymous users (re:
JENKINS-8214), breaks the 'Subproject' view in a job page when the user has permission to the current job, but not the subproject.
Without Discover permission:
User sees 'Unresolved' and the project name under Subprojects. The use can also see the 'Permalinks' section.
With Discover permission on for anonymous:
Subprojects and Permalinks are gone. Instead, there is a jenkins login page embedded in the job.