Revert behavior from a5684dfa3c16472bfa5d5d861ba78cb6dbadcb59 and ensure after_initializer is executed after to_prepare callbacks.

actionpack/lib/action_dispatch/middleware/callbacks.rb

@@ -37,7 +37,7 @@ def self.after(*args, &block)
 
     def initialize(app, prepare_each_request = false)
       @app, @prepare_each_request = app, prepare_each_request
-      run_callbacks(:prepare) unless @prepare_each_request
+      run_callbacks(:prepare)
     end
 
     def call(env)

railties/lib/rails/application/finisher.rb

@@ -27,19 +27,16 @@ module Finisher
         end
       end
 
-      # Fires the user-supplied after_initialize block (config.after_initialize)
-      # Should run before the middleware stack is built, because building the
-      # middleware already fires to_prepare callbacks in test and production.
+      initializer :build_middleware_stack do
+        app
+      end
+
       initializer :after_initialize do
         config.after_initialize_blocks.each do |block|
           block.call(self)
         end
       end
 
-      initializer :build_middleware_stack do
-        app
-      end
-
       # Disable dependency loading during request cycle
       initializer :disable_dependency_loading do
         if config.cache_classes && !config.dependency_loading

railties/test/application/initializers/initializers_test.rb

@@ -52,9 +52,22 @@ def setup
       assert $activerecord_configurations['development']
     end
 
-    test "after_initialize happens before to_prepare (i.e. before the middleware stack is built) on production" do
+    test "after_initialize happens after to_prepare in development" do
       $order = []
       add_to_config <<-RUBY
+        config.cache_classes = false
+        config.after_initialize { $order << :after_initialize }
+        config.to_prepare { $order << :to_prepare }
+      RUBY
+
+      require "#{app_path}/config/environment"
+      assert [:to_prepare, :after_initialize], $order
+    end
+
+    test "after_initialize happens after to_prepare in production" do
+      $order = []
+      add_to_config <<-RUBY
+        config.cache_classes = true
         config.after_initialize { $order << :after_initialize }
         config.to_prepare { $order << :to_prepare }
       RUBY
@@ -62,8 +75,7 @@ def setup
       require "#{app_path}/config/application"
       Rails.env.replace "production"
       require "#{app_path}/config/environment"
-      assert [:after_initialize, :to_prepare], $order
+      assert [:to_prepare, :after_initialize], $order
     end
-
   end
 end