title: Accidentally added other's commits to my PR using git rebase
body: <p>I was going to do more work on a feature and before coding i ran <code>git pull --rebase upstream master</code>. Then ran <code>git push origin feature-branch</code>; this resulted in one of those 'fast-forward' errors in which I then ran <code>git pull origin feature-branch</code>. Following that I fixed a merge conflict and ran <code>git push origin feature-branch</code> again. Now my pr from <code>feature-branch</code> to <code>master</code> is polluted with other's commits. I noticed this questions was asked previously but never <a href="https://stackoverflow.com/questions/49969437/git-pull-rebase-upstream-master-pollutes-my-github-pr-diff">answered</a>. </p>
  
  <p>Can someone explain what I did wrong and maybe how to fix it? </p>