I changed my password via the web interface. And now I can\'t run any command that requires authentication. Password is using plain ASCII, nothing fancy, no Unicode, weird non-p
For all the future error-Googlers out there:
The issue from 2013 has been fixed, however, after you change your password on the website, use the command:
heroku login
You will be prompted for your Heroku login and your new password. Goodbye weird "Authentication success. Authentication failure." errors.
via the Heroku docs: https://devcenter.heroku.com/articles/authentication, about half-way down the page.