I'm not sure if this counts as a bug.  The villager hitbox is too tall for them to pass through a door with a block above it if they are standing on a carpet.  They still recognize the door as a valid part of a village and will repeatedly open and close it, trying to pass through.  Other entities of comparable sizes, such as the player, can fit through under the same circumstance.  This places an unnecessary limit on building, as I can't place carpets next to doors if I want villagers to be able to pass through.