title: Problems with git branches
body: <p>I submitted code to a github project through a git pull and it worked fine : <a href="https://github.com/ivaldi/brimir/pull/245" rel="nofollow">https://github.com/ivaldi/brimir/pull/245</a></p>
  
  <p>Now I am submitting new changes, but the pull also include all the commits from the previous pull : <a href="https://github.com/ivaldi/brimir/pull/257" rel="nofollow">https://github.com/ivaldi/brimir/pull/257</a></p>
  
  <p>The maintainer want me to clean the commits before he merge, but how do I do that?</p>
  
  <p>EDIT : one thing i do not understand is that in my pull request, i have commits with hash that already exist in the master branch. How do i make my submit aware that thoses commits are already in the master?</p>
  
  <p>EDIT 2 : I think Iknow where the problem come from, I pulled the change from my first change from my branch because they were not yet accepted in the master. I also pulled the change from master origin from my first branch, so now it want to push thoses already existing commits to origin master.</p>