[pulse][0/5] MustBeValid should be removed in the pre, not the post
[pulse][0/5] MustBeValid should be removed in the pre, not the post

Summary:
That was just broken before, but apparently nothing cared. It's needed
for the next diffs.

Reviewed By: skcho

Differential Revision: D28674731

fbshipit-source-id: 2f080238b

jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer