This bug took place in a standard Superflat world in a naturally generated village.
This bug is tricky to explain. Basically Villager AI is a bit wonky, some Villagers getting stuck in the doorways and just standing there, or Villagers queueing up near the steps to a door, as well as standing there awkwardly before dashing off to their next destination. (I believe there was an issue with AI calculations with Zombies similar to this)
TL;DR: Wonky villager AI!
Good Luck!
Is this still an issue in the current Minecraft Snapshot 15w45a or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Mob AI got updated in the recent snapshots. Might be fixed.