I use RT 3.4.4, and I have noticed that after you merge a ticket
with a previous one, you can’t switch to any of previous tickets
with the “Prev” link.
As an example: we have merged 340 and 339 and
RT is displaying Ticket #340. But the “Prev” link points to the ticket
#340 too, which is now a replacement for #339. It is impossible to go
somewhere else with “Prev” link now.
I do not treat this as a bug, but the issue should be known anyway.
Maybe there are ways to fix this - it would be pretty nice.