Comment 1 for bug 712403

This happens when the information type of the base branch in the stack is is made confidential, and it was not shared with the owner of the top branch. This will rarely happen with projects that properly share with trusted teams. This mostly happens for projects that have not shared with their trusted teams and did not setup proper sharing policies when the project was setup. Sometime after developers have started work, the project's data is locked down, then the developers discover they are locked out.