title: Effects of git remote update origin --prune on local changes
body: <p><strong>Please note</strong>: I first took a look at <a href="https://stackoverflow.com/questions/20106712/what-are-the-differences-between-git-remote-prune-git-prune-git-fetch-prune">this question</a> hoping it would answer my question, but I think mine is <em>slightly</em> different!</p>
  
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  <p>I was told that running <code>git remote update origin --prune</code> locally would force my local repo to have the exact same branches as the origin repo. However I can find <em>loads</em> of info/documentation surrounding the use of <code>git remote prune origin</code>, but not <code>git remote update origin --prune</code>...</p>
  
  <p>Is my understanding of this command correct? If not, how am I misled? And if I am correct, then what happens if I have local feature branches that haven't been pushed remotely yet? What happens if I have changes to branches that <em>do</em> existing remotely/on the origin but have I have not pushed those changes yet?</p>
  
  <p>Thanks in advance!</p>