title: Compare schema files in different repos
body: <p>I have 4 different git repositories, one local and three deployed on Heroku.</p>
  
  <p>I'm looking for a fast way to check differencies in the <code>schema.rb</code> file, in case a migration or db reset has been forgotten in any of the apps.</p>
  
  <p>I assume that basing on the solution given in <a href="https://stackoverflow.com/a/21101644/3205492">this SO question</a> I would be able to fast check this difference? <code>git diff ref1:path/to/file1 ref2:path/to/file2</code></p>
  
  <p>I have named the remote repositories, i.e. remote_1, remote_2 etc.</p>
  
  <p>I'm unsure though how to apply remote-names + path to get it right on Heroku, any advice on how the correct git command would look like with the above setup?</p>