Comment 0 for bug 1278686

it is that, if the confirmation is launched through admin user,
then the project_id and user_id in context are all admin's, which
result in reservations in DB are also have wrong project_id and
user_id, when these reservations are committed, the quotas usage of
the instance's project/user will become wrong eventually.

this bug can be reproduced both in stable havana and master.
so we need to backport this fix patch to stable havana.

this bug is same as 1271429.