title: push local master *into* gh-pages branch on github
body: <p>I created a simple gh-pages branch on github and in my local repo.  I used the auto page generator to create the 5 files it uses: 
       images  javascripts  stylesheets  index.html  params.json</p>
  
  <p>I pulled this to my local repo and added js-markdown-extra.js to javascripts, and edited index.html to replace the "content" section with the compiled README.md created by the markdown library.</p>
  
  <p>Putting in a dummy README.md showed it to work perfectly.</p>
  
  <p>I <em>want</em> to then simply push my local master <em>into</em> (not <em>onto</em>) the remote gh-pages branch, without modifying the 5 website files.</p>
  
  <p>I haven't found a way to do this.  I was told via <a href="http://oli.jp/2011/github-pages-workflow/" rel="noreferrer">http://oli.jp/2011/github-pages-workflow/</a> that this would work: git push -f origin master:gh-pages</p>
  
  <p>I tried this on a test repo and it failed, resulting in a 404 (pushing the local gh-pages made for the markdown trick fixed that)</p>
  
  <p>So <em>is</em> there a way to push master <em>into</em>, as a subset of, gh-pages? </p>
  
  <p>Failing that, is there a simple way to merge the master into gh-pages locally without deleting the 5 website files?</p>
  
  <p>I know how to "mirror" all this stuff so the 5 files would be in the repo but I'd like to avoid that clutter.</p>