When someone sends you a pull request from a fork or branch of your repository, you can merge it locally to resolve a merge conflict or to test and verify the changes before merging on GitHub.
S. Perez De Rosso, и D. Jackson. Proceedings of the 2013 ACM International Symposium on New Ideas, New Paradigms, and Reflections on Programming &\#38; Software, стр. 37--52. New York, NY, USA, ACM, (2013)