app-prefix for tasks defined in an engine?!

[vierund...@googlemail.com]

I have defined a rake task inside an engine like this: 

rake app:redmine_config:spec

namespace :my_engine do 

  

  desc "say foo"

  task :foo do

    puts "foo from the engine"

  end

end

I expected the task to be available under

rake my_engine:foo

instead I found it under: 

rake app:my_engine:foo

Does anybody have an idea where the prefix comes from? Can I change it? Can I get rid of it?

thx for any help, 

stefan