title: Gerrit: Working with already existing git repos
body: <p>I want to introduce gerrit into my soft dev environment. The issue is that I already have existing git repos... 
  I was able to install gerrit and get a copy of already existing repos by executing following command: <code>git clone --mirror ssh://some_machine/path/to/favourite/project.git project.git</code></p>
  
  <p>But now, I need to sync the changes back to original repos. Is there a way to do it or do I need to move completely to new repos handled by gerrit and block already existing git repos so that developers won't be able to check stuff into them?</p>
  
  <p>Sorry, very new to gerrit...</p>