rake -P output is ambiguous with prereq namespaces

rake -P/--prereqs の出力エントリポイントから開始し、issue に示されている Rakefile を再現します。tool:run と tool:run2 の namespaced prerequisite がどのように解決されるかを追跡し、その後、両方について表示される prerequisite が完全修飾され、曖昧でないことを確認します。

When tasks are in a namespace, their pre-reqs "inherit" the namespace prefix.

Given the following rakefile:

task :setup do
  puts "global setup, oops"
end

namespace :tool do
  task :setup do
    puts "setting up"
  end
  task run: :setup do
    puts "running"
  end
  task run2: 'tool:setup' do
    puts "running a second way"
  end
end

The both tasks run and run2 have the same pre-req (setup). However, task run omits the namespace, while run2 is explicit with its pre-req's namespace. Both forms work as expected:

$ rake tool:run
setting up
running

$ rake tool:run2
setting up
running a second way

However, when the pre-req tree is printed, rake is not clear about what the pre-reqs' full names are.

$ rake -P
rake setup
rake tool:run
    setup  # <--- This is ambiguous!
rake tool:run2
    tool:setup
rake tool:setup

The expectation is that rake -P prints the "fully resolved" pre-reqs and is thus clear about what task will actually be run. In the example above, it is not clear what tool:run's pre-req is. Is it the "global" setup, task as it appears in the -P output? Or is it in fact tool:setup because it is namespaced?

To be clear, rake's invocation behavior matches my expectations: tool:run invokes tool:setup, not setup. But this behavior is not evident in rake's --prereqs output.