Revert "Whoops. set_instances_variables_work != set_instance_variables_create."

This reverts commit 3b1ed2c57a855fd9ec825f45f0ab1e7a12953797.
Revert "Split out some helper functions for WorksController#set_instance_variables"

This reverts commit ff8b478831a0c43fb621b2cd1f8a924b177e4cfe.