nur@nursulaeman:~/timeup/timetracker1$ heroku run rake db:migrate
Running `rake db:migrate` attached to terminal... up, run.3311
  ActiveRecord::SchemaMigration Load (1.2ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Migrating to AddDeviseToUsers (20150808142421)
   (1.1ms)  BEGIN
== 20150808142421 AddDeviseToUsers: migrating =================================
-- change_table(:users)
   (44.8ms)  ALTER TABLE "users" ADD "encrypted_password" character varying DEFAULT '' NOT NULL
   (1.4ms)  ALTER TABLE "users" ADD "reset_password_token" character varying
   (1.3ms)  ALTER TABLE "users" ADD "reset_password_sent_at" timestamp
   (1.4ms)  ALTER TABLE "users" ADD "remember_created_at" timestamp
   (50.0ms)  ALTER TABLE "users" ADD "sign_in_count" integer DEFAULT 0 NOT NULL
   (1.3ms)  ALTER TABLE "users" ADD "current_sign_in_at" timestamp
   (1.3ms)  ALTER TABLE "users" ADD "last_sign_in_at" timestamp
   (1.3ms)  ALTER TABLE "users" ADD "current_sign_in_ip" inet
   (4.6ms)  ALTER TABLE "users" ADD "last_sign_in_ip" inet
   -> 0.1138s
-- add_index(:users, :email, {:unique=>true})
   (33.6ms)  CREATE UNIQUE INDEX  "index_users_on_email" ON "users"  ("email")
PG::UniqueViolation: ERROR:  could not create unique index "index_users_on_email"
DETAIL:  Key (email)=() is duplicated.
: CREATE UNIQUE INDEX  "index_users_on_email" ON "users"  ("email")
   (1.2ms)  ROLLBACK
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

PG::UniqueViolation: ERROR:  could not create unique index "index_users_on_email"
DETAIL:  Key (email)=() is duplicated.