NoMethodError with rake db:migrate

Hi! First of all, this is my first application on Rails, and i'm stuck at a
migration. i created a demo app (the demo_app from michael hartl's tutorial)
as usual: rails new demo_app, rails generate scaffold User name:string
email:string, and when i do rake db:migrate, this stack appears:

rake db:migrate --trace
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
rake aborted!
NoMethodError: undefined method `to_a' for #<SQLite3::Statement:0x9d6a2dc>:
          FROM sqlite_master
          WHERE type = 'table' AND NOT name = 'sqlite_sequence'
AND name = "schema_migrations"

This is the Gemfile:

source ''

gem 'rails', '3.2.8'

# Bundle edge Rails instead:
# gem 'rails', :git => 'git://'

gem 'sqlite3'
gem 'sqlite3-ruby', '1.2.5', :require => 'sqlite3'

Are those the versions of rails (3.2.8) and sqlite3-ruby that the
tutorial expects? I don't know but I suspect that a later version of
sqlite3-ruby might fix it. Googling for the error message finds this
for example