In katello's use case all repositories that sync need to use the same proxy information. If the user needs to change it we need to change it for all repos. This is a bit cumbersome and error prone so it would be fantastic if we could just set a global default in server.conf instead of the global default being 'no proxy'.
A plugin can have a conf file that Pulp will load and make accessible. We can store the info in the yum importer's conf file.
Fixed in 2.0 in a different bug, marking this one as a duplicate. *** This bug has been marked as a duplicate of bug 878548 ***