develop now contains the as_deprecation_tracker test dependency to track
known deprecation warnings. This helps prevent new code being committed
that depends on deprecated functionality, and will warn you (by failing
tests) of existing usage that becomes deprecated, either by Rails or
Foreman.
It's disabled for plugins, but there's now information on the wiki for
any developer who wishes to enable and use it there:
http://projects.theforeman.org/projects/foreman/wiki/How_to_Create_a_Plugin#Testing-for-deprecations