As some of you may be aware, `parent.config` files generated by Traffic Ops can
vary wildly when an origin is assigned to multiple Delivery Services. This
results in undefined behavior. I'm told that the conflict only happens when two
Delivery Services with different "topology requirements" use the same origin,
whatever that means (content routing type?). Regardless, the issue should be
addressed. The obvious solution is to put in place a database constraint that
prevents an origin from being assigned to more that one Delivery Service with
API checks in place that would provide helpful error messages when an attempt
is made to violate the constraint. However, would that mess with things like
Multi-Site Origin? Or is it just not viable for some other reason? If it is a
good solution, I'm prepared to work on a fix that utilizes it.
