title: Undo "Reverting a pull request"
body: <p>I merged a PR on Github and had to revert it, so I used the revert button on the Github interface to do it.
  A new PR was made from the same branch the reverted one was made, but with a few additions. When I merge the new PR, some changes part of the old PR are missing.</p>
  
  <p>Note that some commits were added after the reversion</p>
  
  <p>I'm thinking of using the Github UI to again revert the previous reversion, but I'm not sure what this will do, can't find any documentation relating to that.</p>
  
  <p>I'm curious to know why the code is getting lost and how I could avoid this. Also what's the best way to resolve this, use the revert option again?</p>
  
  <pre><code>ed3240aa (HEAD -&gt; version/2, origin/version/2) Merge branch 'version/2' of github.com:umbrella/app into version/2
  8d7b6a8f Bump version of app
  8b268172 Fix error in condition for disavowing excluded alerts
  a12eca40 Point app to staging
  5c83c0bb Merge pull request #1090 from umbrella/revert-1088-add-sentiment   // Merge PR with reversion
  3ab766fc Revert "Add sentiment insight"                                     // Revert happened here
  132a9e64 Merge pull request #1089 from umbrella/nana_sources
  acaec5e0 Merge branch 'version/2' into nana_sources
  881925d7 - finished showing the dimension sources
  df0b0ead Merge pull request #1088 from umbrella/add-sentiment
  5bc3165d Merge pull request #1087 from umbrella/sync-exclude
  c6936a2e (origin/sync-exclude, sync-exclude) Remove spurious logs
  </code></pre>