title: Undo git merge (and push to heroku)
body: <p>This question has been asked too many times but I am not finding solution to my situation, and so will ask it again. I have 2 branches - master and residents. I have been working on residents for about 2 months, basically a complete redesign of a form (tons of check_boxes, radio_buttons etc. to avoid typing). Approximately 35 commits. Couple of times or so I have done minor changes in the master and merged the master into the residents. Then when I was happy with the residents, I switched to the master, merged the residents into it and pushed to heroku. </p>
  
  <p>The app (actually, the form containing some JS) doesn't work on heroku (it does on my local). I rolled back on heroku, and now I need to return the app to the state before the merge and push. I have the residents branch, so all I need is to discard the entire merge from the master.</p>
  
  <p>I think this should be an easy undo, but I didn't find out how.</p>
  
  <p>Thanks for help.</p>