[confirmed]Avacyn, Guardian Angel doesn't validate targets

Describe the Bug:
If Avacyn, Guardian Angel's target stops being valid between announcement and resolution - it stops being a creature (for the first ability), gains shroud or hexproof or protection from white, etc. - damage to it is still prevented.
Which card did behave improperly ?
Avacyn, Guardian Angel.
Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
Dev master head, 6287802.
What exactly should be the correct behavior/interaction ?
The target has to be valid at announcement and resolution, same as always. (It doesn't still have to be valid after that, when the damage is actually prevented, which its ruling states explicitly: 7/18/2014: Whether the target permanent or player is still a legal target is no longer checked after the appropriate ability resolves. For example, if a creature targeted by the first ability gains protection from white after the ability resolves but before it prevents damage, the effect will still prevent damage.)
Are any other cards possibly affected by this bug ?
I haven't seen any yet.
If Avacyn, Guardian Angel's target stops being valid between announcement and resolution - it stops being a creature (for the first ability), gains shroud or hexproof or protection from white, etc. - damage to it is still prevented.
Which card did behave improperly ?
Avacyn, Guardian Angel.
Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
Dev master head, 6287802.
What exactly should be the correct behavior/interaction ?
The target has to be valid at announcement and resolution, same as always. (It doesn't still have to be valid after that, when the damage is actually prevented, which its ruling states explicitly: 7/18/2014: Whether the target permanent or player is still a legal target is no longer checked after the appropriate ability resolves. For example, if a creature targeted by the first ability gains protection from white after the ability resolves but before it prevents damage, the effect will still prevent damage.)
Are any other cards possibly affected by this bug ?
I haven't seen any yet.