admin: change the subject computing list
admin: change the subject computing list

The tests have to be modified slightly, because they slipped this case
through. If the form input was '' or '-', both None and the input value
would be added to storage.

paulsnar/edaemon,p22co/edaemon,paulsnar/edaemon,paulsnar/edaemon,p22co/edaemon,p22co/edaemon