Evokers / vindicators / illusioners / pillagers have a gap between their legs

The bug

As of 18w50a; evokers, vindicators, illusioner and pillagers have a gap between their legs. However, villagers, zombie villagers and witches don't have this but they look-alike (or use the same base model). Also, neither do other mobs with legs have a gap, this looks weird and is inconsistent with other mobs.