Open pull request page at github.com, click the link "command line".

In a real world project, I rarely accept a pull request without some modification. So I usually avoid pressing the big green button "merge pull request" on that page.

In the "command line" page, github is kind enough to list the command lines to "check out a new branch and test the changes" from the pull request. The command lines are like:

git checkout -b her-master master git pull git@github.com:her/myproject.git master

I have installed a Greasemonkey user script NinjaWebCoder in order to use keyboard to copy those command lines from the browser into clipboard. Then I paste the command lines into terminal.