Allow collaborators to view repo owned private org (#6965)

Handle case where an orginization is private but a user who is not a
member of the orgninization has been added as a collaborator of a repo
within that org

Fixes #6962

models/fixtures/collaboration.yml

@@ -9,3 +9,9 @@
   repo_id: 4
   user_id: 4
   mode: 2 # write
+
+-
+  id: 3
+  repo_id: 40
+  user_id: 4
+  mode: 2 # write