Validates Format is NOT Case Sensitive

I could not reproduce this on the 3-0-stable branch.

I did the following:

• Create a new app
• Create a Post scaffold with title field
• Add the validation: validates :title, :format => { :with => /[a-z]+/ }
• Try the following in console

ruby-1.9.2-p0 > p = Post.new :title => 'ABC'
 => #<Post id: nil, title: "ABC", created_at: nil, updated_at: nil> 
ruby-1.9.2-p0 > p.save
 => false 
ruby-1.9.2-p0 > p.errors
 => {:title=>["is invalid"]} 

ruby-1.9.2-p0 > valid_p = Post.new :title => 'abc'
 => #<Post id: nil, title: "abc", created_at: nil, updated_at: nil> 
ruby-1.9.2-p0 > valid_p.save
 => true

Are there any other steps that need to be followed to reproduce this issue?