As noted in the title, dungeons spawn mobs regardless of how well lit the room is. This was first noticed in 14w26c, but could have occurred in prior snapshots, but not before 14w21b. This was discovered after encountering two previously explored dungeons. The dungeons held a light level of 10-12. When the mobs spawned, roughly 75% of the spawns were half in blocks, if not fully, leading some to suffocate.