Hi there, this is Greg, bringing you the changes in Rails from the past week. Let's dive in!
This commit adds a slight performance improvement by reducing stat(2) calls in Rails.
This PR updates the immutable string class to serialize symbols to strings to mirror this behavior as ActiveModel::Attribute calls this serialize method to determine the return value for changed_in_place?. Prior to this change, this code would wrongly report that "something" had changed.
This PR makes it possible to set a different log level on a per request basis. 

# Use the debug level if a particular cookie is set.
class ApplicationController < ActionController::Base
  log_at :debug, if: -> { cookies[:debug] }

25 people contributed to Rails last week, if you want to be part of that, check out the open issues on Github. 
Until next time.