Parameter deletion within an Array

[jonesdeini]

In Rails 4.X this is fixed:

2.2.2 :001 > params = ActionController::Parameters.new
 => {} 
2.2.2 :002 > params[:foo] = ['bar'] 
 => ["bar"] 
2.2.2 :003 > params
 => {"foo"=>["bar"]} 
2.2.2 :004 > params[:foo].delete 'bar'
 => "bar" 
2.2.2 :005 > params
 => {"foo"=>[]} 

Rails 3.1 with strong_parameters

1.9.3-p551 :001 > params = ActionController::Parameters.new
 => {} 
1.9.3-p551 :002 > params[:foo] = ['bar'] 
 => ["bar"] 
1.9.3-p551 :003 > params[:foo].delete 'bar'
 => "bar" 
1.9.3-p551 :004 > params
 => {"foo"=>["bar"]} 
1.9.3-p551 :005 > 

This is caused by this line. As the array returned is no longer the same object (verified by calling #object_id).

I'm currently working on a fix, but I figured I should create an issue so others can know about this.
I have failing test here