Code review comment for lp:~sinzui/launchpad/entitle-branch-sharing

This can't land before <https://code.launchpad.net/~sinzui/launchpad/commercial-admin-sharing/+merge/120464>, as in this branch there's no access check at all on setBugSharingPolicy or setBranchSharingPolicy. If your new permission from the other branch is sufficient, perhaps remove the unused user argument from setFooSharingPolicy.