weird rails association behavior

gistfile1.rb

$> rails new mynewapp
$> cd mynewapp
$> rails g model User
$> rails g model Whatever
$> rake db:migration

#user.rb
belongs_to :whatever

$> rails c
     u = User.new
     u.save
     w = Whatever.new
     w.save
     u.whatever = w
     u.save #no error!  
     
     u.whatever               #=> w(Whatever)
     u.reload                 #=> w(Whatever)
     User.find(u.id).whatever #=> nil!!!!!!