title: updating local master with remote master
body: <p>I have a branch that I want to merge to the remote, most up-to-date <code>master</code>. I have a local, outdated master on my computer. 
  I ran <code>git pull upstream master</code>, and it retrieved the remote <code>master</code>, and that was great, exactly what I wanted. Then, without thinking, i accidentally discarded the changes while switching to another branch. </p>
  
  <p>While on my local master, I have run <code>git pull</code>, and <code>git pull upstream master</code> many times now, and it always says "Already up to date." when it clearly isn't. At first <code>git pull upstream master</code> worked just fine, but now it doesn't, and the machine thinks it is up to date when it isn't. How can I make my local master the same as the remote one again?</p>