How do you think the file was missed in the original land?

I landed both D6398 and D6399 at the same time by patching in D6399 by using arc patch D6399. My theory is that I didn't update D6399 in Phab with the rebase, which caused the file to be dropped. In the future, I will be more careful with this.

Encourage you to only use arc patch for pulling in other people's work going forward – it's typically a "crutch" for not understanding git well enough. Try to use git cherry-pick if you need to get a commit from another branch into the current one

In D6412#192153, @ashoat wrote:

Encourage you to only use arc patch for pulling in other people's work going forward – it's typically a "crutch" for not understanding git well enough. Try to use git cherry-pick if you need to get a commit from another branch into the current one

Gotcha moving forward I will make sure to do that