Summary:
When watchman returns is_fresh_instance=True, it means the old clock value
cannot help watchman to do less work. Therefore the clock value needs to be
updated to make the next status call faster.
Reviewed By: phillco
Differential Revision: D8714863
fbshipit-source-id: 1eb2bf876b21bd0f17134a3b93b06b759746fd4c
