Fixed #17895 -- Made override_settings send the setting_changed signal both...

Fixed #17895 -- Made override_settings send the setting_changed signal both when a setting is overridden and when it's restored.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@17708 bcc190cf-cafb-0310-a4f2-bffc1f526a37