any propagation for unionT
any propagation for unionT

Summary: We can defer the any propagation to the cases that handle the parts of the union.

Reviewed By: samwgoldman

Differential Revision: D10275704

fbshipit-source-id: 689baa621d4bffea2b131df9dbe34742cf8cc50a

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow