Comment 0 for bug 995324

Here is a pretty intricate problem. Assume a folder contains messages

  M1: Subject A
        M2: Subject A

and subject threading has grouped M1 and M2 together.

If M2's parent (say P) with a different subject B gets inserted into the folder, VM's threading database becomes inconsistent.

M2's thread-list is reset. However, M1's thread-subtree still contains M2. The subject node for "A" seems to retain M2 as well.