app-prefix for tasks defined in an engine?!

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”



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,