title: Include only specific commits in a pull request
body: <p>Let's say I have cloned repository, created new branch "Topic1", made changes, commited them and then pushed them to a remote repo <code>git push origin Topic1</code>. After that I made a pull request into master branch.</p>
  
  <p>Then on my local repository I checkout from branch "Topic1" to branch "Topic2", made some changes there, commited and again pushed this new branch to remote. And again made a pull request into master. I want to mention that in the meantime no changes were made to master branch, so I didn't need to sync my local repo with upstream.</p>
  
  <p>And here's the problem: when I go to pull request page of "Topic2" all the commits of "Topic1" are presented there. So, my question - how can I get in 2nd pull request commits related only to "Topic2" branch?</p>