I originally posted it as a bug report and was asked to post it as a suggestion here.
If you merge two posts... IPB does two things:
1. It merges the two threads without asking me which thread I want it to pick as the new parent one.
1. It kills the link of the second thread. It becomes 404.
What I want IPB to do is to ask me which thread I want to keep after the merge. And I want it to redirect the second thread to link to the merged thread.