title: Are dependent pull requests in Github possible?
body: <p>Currently I am working on a really big pull request. In order to keep code-reviews somehow manageable the idea was to split the complete pull request in isolated parts, which however depend on each other.</p>
  <p>An example would be:</p>
  <ul>
  <li><strong>Pull request 1</strong>: Create interfaces: Interface A &amp; B and restructure code</li>
  <li><strong>Pull request 2</strong>: Interface A implementation and Tests (depends on pull request1)</li>
  <li><strong>Pull request 3</strong>: Interface B implementation and Tests (depends on pull request2)</li>
  <li><strong>Pull request 4</strong>: Mixed test of Implementations (depends on 2 + 3)</li>
  </ul>
  <p>Is there a way in Github to file all four pull requests at the same time with dependencies?</p>