Accessing a project URL fails with 'Not Found - The page you requested
was not found, or you do not have permission to view this page' if the
user is not signed in and the project is not visible to 'Anonymous
Users'. Instead Gerrit now asks the user to login and afterwards shows
the project to the user if it exists and is visible. If the project
doesn't exist or is not visible, the user will still get the
NotFoundScreen after sign in. Since we always show the sign in dialog
when the user is not signed in and a project is not found, a user
can't probe project URLs to find out whether a project exists or not.
Change-Id: I99a6ece039dbfa628c07165d6f16d9a70bf3ebae
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>