Revert "Fixing typo"

This reverts commit 4f4abeb73e2054eb616b43f434046a0b89d14f93.
Revert "Fixing bug in creation of cache keys tuple"

This reverts commit e189ab80f74c44fc7330789988001e2051d865f3.
Revert "Making fk lookups optional when invalidating objects"

This reverts commit ce61fcf7845623cc75fab44172e1ae2a9ea24688.