git clone https://github.com/github/dmca.git .
git fetch origin 416da574ec
git branch youtube-dl 416da574ec
git checkout -f youtube-dl
git fetch origin 416da574ec
git branch youtube-dl 416da574ec
git checkout -f youtube-dl
fatal: Couldn't find remote ref 416da574ec
`git fetch origin pull/8142/head` worked (the ref became available).