Sponsorship list checks permissions for current release

This is pretty corner case, but the sponsorship queue appears to use the current release when seeing if the most recent commentor can upload the package in question.

The current example in the queue is lp:~mathieu-tl/ubuntu/lucid/wpasupplicant/dbus-pkcs11-eapol/+merge/87780. Mathieu can upload wpasupplicant to precise because wpasupplicant is currently in the network-manager packageset, but it was not for Lucid, so Mathieu should not be marked as a developer who can upload the package.

ubuntu-dev-tools grew an ubuntu-upload-permission script - the logic there might be helpful.