[pulse] defend in depth against false leaks
[pulse] defend in depth against false leaks

Summary:
It's unclear whether this can happen but it doesn't cost much to do a
last check before reporting an error to the user.

Reviewed By: skcho

Differential Revision: D28382670

fbshipit-source-id: e23f07ebd

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