As of 15w39c, Villagers are once more clustering in the north-west corner of their villages. This was not the case in the 15w38 builds.

Note in the attached screenshot, I'm standing 'one building away' from the NW corner of the village. Behind me are roughly 30 buildings.

– Edit –

2 Months later and this bug has still not been acknowledged, let alone addressed. It'd be really nice to see some attention to this issue since it's a regression bug and one that was a real pain before it was fixed the first time. I understand that bugs need to be triaged and prioritized, but I'm really starting to worry that this regression is going to make it to the release build.

– Edit –

Behavior is still present in 15w49b