Non-golem pet monsters and AI

[SilverNexus]

Using both the trunk server and client (r18496), I noticed the following:

When using spells like summon pet monster, magehound, or obtaining allies through oratory, I noticed they all have a tendency to pick out an enemy to attack that is several spaces away from them, yet find themselves unable to reach their desired target because there are other monsters in the way. These other monsters, noticing the pet that is trying desperately to reach another monster, start to attack the pet.
The pet, however, ignores the monsters now attacking it and tries to go for the target it already had.

I have seen something similar to this behavior in regular monsters as well. As soon as they set their sights on a player, they go exclusively for that player, even if other players attack them. Sometimes, when one player enters a map a minute or two before another player, the monsters will fail to notice the second player entirely, and will begin to pursue the first player when attacked by either player.