[confirmed]Graf Rats skips combat trigger

[Korath]

Describe the bug:
If I cast Graf Rats and Midnight Scavengers during my precombat main phase, have no other creatures that can attack or anything that gives them haste, and click the shiny brown "Done" button instead of the combat phase icon, it doesn't trigger.

Which card behaved improperly?
Graf Rats: | Creature - Rat | 2/1 | At the beginning of combat on your turn, if you both own and control Graf Rats and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.
Midnight Scavengers: | Creature - Human Rogue | 3/3 | When Midnight Scavengers enters the battlefield, you may return target creature card with converted mana cost 3 or less from your graveyard to your hand.
Chittering Host: - | Creature - Eldrazi Horror | 5/6 | Haste / Menace (This creature can't be blocked except by two or more creatures.) / When Chittering Host enters the battlefield, other creatures you control get +1/+0 and gain menace until end of turn.

Which update are you using? (date, name)Which type? (duel, gauntlet, sealed deck)
Dev 4721c01.

What exactly should be the correct behavior/interaction?
There's always a combat phase, unless something explicitly causes it to be skipped. (The declare blockers and combat damage steps are skipped if no creatures attack, per rule 506.1.)

Are any other cards possibly affected by this bug?
Just about everything else with a start-of-combat or end-of-combat trigger, I'd imagine. I seem to recall it being a problem with Xenagos, God of Revels.

[Aswan jaguar]

Graf Rats//Chittering Host - Midnight Scavengers//Chittering Host for autocard reference.

You are right for Xenagos, God of Revels we adopted the put a stop :
viewtopic.php?f=110&t=13761&p=146774&hilit=%2C+God+of+Revels#p146774