% rake secret
[GENERATED TOKEN]
% heroku config:add SECRET_TOKEN=[GENERATED TOKEN]
% rm config/initializers/secret_token.rb
% rake secret:generate
% git update-index --assume-unchanged config/initializers/secret_token.rb
% rake secret
[GENERATED TOKEN]
% heroku config:add SECRET_TOKEN=[GENERATED TOKEN]
% rm config/initializers/secret_token.rb
% rake secret:generate
% git update-index --assume-unchanged config/initializers/secret_token.rb