Merge pull request rails#42719 from jdelStrother/hash-optimization

Micro-optimize ActiveRecord::Core#hash

Author: rafaelfranca

activerecord/lib/active_record/core.rb

@@ -601,6 +601,8 @@ def ==(comparison_object)
     # Delegates to id in order to allow two records of the same type and id to work with something like:
     #   [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
     def hash
+      id = self.id
+
       if id
         self.class.hash ^ id.hash
       else