This question already has an answer here:
I've forked from a repo on GitHub. I want to get the code from a branch on another user's fork.
Must I clone this user's whole repo to a separate local repo or can I do something like git checkout link_to_the_other_users_branch?
$ git remote add theirusername git@github.com:theirusername/reponame.git
$ git fetch theirusername
$ git checkout -b mynamefortheirbranch theirusername/theirbranch
Note that there are multiple "correct" URIs you can use for the remote when you add it in the first step.
git@github.com:theirusername/reponame.gitis an SSH-based URIhttps://github.com/theirusername/reponame.gitis an HTTP URI
Which one you prefer to use will depend on your situation: GitHub has a help article explaining the difference and helping you choose: Which remote URL should I use?
amalloy's suggestion didn't work for me. This did:
git remote add theirusername https://github.com/theirusername/reponame
git fetch theirusername
git checkout -b mynamefortheirbranch theirusername/theirbranch
Resources:
来源：https://stackoverflow.com/questions/9153598/how-do-i-fetch-a-branch-on-someone-elses-fork-on-github