Fixed Merging thread breaks link with resource -- sort of

[Jon W]

Steps to reproduce:

• Create a resource in a category where threads are created automatically
• Create a new thread (#2) in the same forum as the above automatically created thread (#1)
• Merge the threads, selecting thread #2 as the one to merge into

This will still leave the link from the resource to the thread intact (because of the redirect) but the link from the thread back to the resource will no longer work exist.

 

[Mike]

In this case, merging into another thread, takes the general thread information from the target record, which isn't associated with the resource.

So in general, I've made this consistent: the discussion association now explicitly checks that the thread is actually the thread it expects (based on discussion_type = resource).