#668 Tickets on Hold don't automatically open again on new mail

[Geir Bćkholt]

If i put a ticket on Hold, it used to re-open if new mails were received to
it. ( it did in 2.0.x )

Now, after upgrading to 2.1, it just sits there with its status as Hold.
Something fires because it gets marked as unread, but it never changes
state to 'open' again.

( I don't know if it is related , but occasionally new mails are received and
its corresponding ticket isnt marked as unread either, so you have to
manually search for new mails. )