Developers with upload permissions cannot reject MPs owned by ubuntu-branches

[Colin Watson]

I had to reject https://code.launchpad.net/~3v1n0/ubuntu/natty/ca-certificates/digicert-certificates/+merge/57086 for Jamie Strandboge because he couldn't change its Status field, even though he has upload permissions for that package by virtue of being an Ubuntu core developer. It seems that this should be one of the pieces of magic associated with the ~ubuntu-branches user (which IIRC is a celebrity): anyone with Ubuntu upload permissions to a package should be able to edit the status of merge proposals against that package in the lp:ubuntu/* namespace.