Desert and Jungle Temples that are partway in swamp biome no longer spawn witches in 1.6.3

Pre 1.6.3 it was possible to have a Desert or Jungle Temple that was in the proper biome, and also partway in a swamp biome.

These structures were previously valid locations for witches to spawn. The code didn't distinguish between a temple, or a witch hut.

In 1.6.3 the Desert and Jungle Temples that are partway in swamp biome no longer spawn witches.

Is this a correction of a defect (witches should not have been able to spawn in temples) ? Or a new bug, that the code (in 1.6.3) that saves the structure data, is not correctly handling temples that span a swamp biome ?

Attached screen shots in 1.6.3, and then in 1.6.2