…ines

and plugins inside engines

It seems that plugins inside a Rails 3.1 application proper (i.e. in
/vendor/plugins) are initialized before engines and plugins inside
engines.

After some debugging, I found the culprit in
Rails::Application::Railties#all:

  def all(&block)
    @ALL ||= railties + engines + super
    @all.each(&block) if block
    @ALL
  end

The call to super here implicitly passes the &block argument, which
has the unfortunate side-effect of adding the plugin initializers
first (in front of other railties and engines) in the case of
Rails::Engine#initializers:

def initializers
  initializers = []
  railties.all { |r| initializers += r.initializers }
  initializers += super
  initializers
end

The solution here is to replace the super call with a call
to #plugins.