title: Why does merging pull request produces two commits?
body: <p>Why does merging pull request produce two commits? Is this normal? Example these two commits are produced after merging pull request</p>
  
  <p><a href="https://github.com/square/retrofit/commit/39394b302809f80c1e089a194862094d16fc3eca" rel="nofollow noreferrer">https://github.com/square/retrofit/commit/39394b302809f80c1e089a194862094d16fc3eca</a></p>
  
  <p><a href="https://github.com/square/retrofit/commit/62a4a8308015f5efb51e20089fb8280d4454ed74" rel="nofollow noreferrer">https://github.com/square/retrofit/commit/62a4a8308015f5efb51e20089fb8280d4454ed74</a></p>