Teletran fetches list of "committers" based on original diff author instead of person who landed the diff

[janephilipps]

I created a diff that was then comandeered by @langtianlang because he had more context. Because I was the original author of the diff, I was pinged in #deploys when the changes were being deployed. This came as a surprise - it seems like the person who lands the diff should be pinged instead of the original author.