title: Heroku login cannot open browser
body: <p>When attampting to login to Heroku via the CLI, I get:</p>
  
  <pre><code>user@MyMachine:$ sudo heroku login 
  heroku: Press any key to open up the browser to login or q to exit: 
  Opening browser to https://cli-auth.heroku.com/auth/browser/SOME-HEROKU-TOKEN
  Warning: Cannot open browser.
  heroku: Waiting for login... !
  </code></pre>
  
  <p>And the login hangs while waiting for the browser.
  When I open the link in the browser and try to login, nothing happens in the CLI.</p>
  
  <p>Using the debugging flags yields:</p>
  
  <pre><code>user@MyMachine:~$ sudo HEROKU_DEBUG=true HEROKU_DEBUG_HEADERS=1 heroku login 
  heroku: Press any key to open up the browser to login or q to exit: 
  Opening browser to https://cli-auth.heroku.com/auth/browser/SOME-OTHER-TOKEN
  Warning: Cannot open browser.
      at Object.warn (/snap/heroku/3776/node_modules/@oclif/errors/lib/index.js:33:15)
      at showUrl (/snap/heroku/3776/node_modules/@heroku-cli/command/lib/login.js:132:34)
      at ChildProcess.cp.on.code (/snap/heroku/3776/node_modules/@heroku-cli/command/lib/login.js:145:17)
      at ChildProcess.emit (events.js:193:13)
      at maybeClose (internal/child_process.js:999:16)
      at Process.ChildProcess._handle.onexit (internal/child_process.js:266:5)
  heroku: Waiting for login... !
  JSONError: Unexpected end of JSON input while parsing near ' '
      at module.exports (/snap/heroku/3776/node_modules/parse-json/index.js:26:19)
      at HTTP._parse (/snap/heroku/3776/node_modules/@heroku-cli/command/node_modules/http-call/lib/http.js:343:25)
  </code></pre>
  
  <p>And again, a hang.</p>