Fixed an issue where reloading of removed dependencies would cause an unexpected circular dependency error

activesupport/lib/active_support/dependencies.rb

@@ -665,6 +665,14 @@ module ActiveSupport #:nodoc:
       constants = normalized.split('::')
       to_remove = constants.pop
 
+      # Remove the file path from the loaded list.
+      file_path = search_for_file(const.underscore)
+      if file_path
+        expanded = File.expand_path(file_path)
+        expanded.sub!(/\.rb\z/, '')
+        self.loaded.delete(expanded)
+      end
+
       if constants.empty?
         parent = Object
       else

activesupport/test/dependencies_test.rb

@@ -948,6 +948,18 @@ class DependenciesTest < ActiveSupport::TestCase
     Object.class_eval { remove_const :A if const_defined?(:A) }
   end
 
+  def test_access_unloaded_constants_for_reload
+    with_autoloading_fixtures do
+      assert_kind_of Module, A
+      assert_kind_of Class, A::B # Necessary to load A::B for the test
+      ActiveSupport::Dependencies.mark_for_unload(A::B)
+      ActiveSupport::Dependencies.remove_unloadable_constants!
+       
+      A::B # Make sure no circular dependency error
+    end
+  end
+
+
   def test_autoload_once_paths_should_behave_when_recursively_loading
     with_loading 'dependencies', 'autoloading_fixtures' do
       ActiveSupport::Dependencies.autoload_once_paths = [ActiveSupport::Dependencies.autoload_paths.last]