Heroku register new key 新しいssh Key
http://stackoverflow.com/questions/8786564/cannot-push-to-heroku-because-key-fingerprint
http://stackoverflow.com/questions/8786564/cannot-push-to-heroku-because-key-fingerprint/8803103#8803103
I had to add my new rsa identity in my machine!
So, first of all I created a new rsa key:
ssh-keygen -t rsa -C "my_name@gmail.com" -f ~/.ssh/id_rsa_heroku
then added to my machine
ssh-add ~/.ssh/id_rsa_heroku
and, finally, to Heroku
heroku keys:add ~/.ssh/id_rsa_heroku.pub
After that,
git push heroku master