(2) Die when there is a problem opening at.allow other then it not existing.
An error other then it not existing might be a trick to somehow
circumvent system security.
Mostly Reviewed By: msmith
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.