Rails - Jun 2006 - revised rake doc:app executes twice

I''m trying to create a new rake task that will generate slightly
customized RDoc
documentation for my Rails app. So I''ve created a new task (shown
below) in
lib/tasks/doc.rake. It generates documentation OK, but it executes the task
twice every time I ''rake doc:custom''.

namespace :doc do
  desc "Generate customized documentation for this application"
  Rake::RDocTask.new(:custom) do |rdoc|
    rdoc.rdoc_dir = ''doc/app''
    rdoc.title    = "System Documentation"
    rdoc.options << ''--line-numbers'' <<
''--all'' #<< ''--inline-source''
    if ENV[''template'']
      puts "using template: #{ENV[''template'']}"
      rdoc.options <<
"--template=#{ENV[''template'']}"
    end
    rdoc.rdoc_files.include(''doc/README_FOR_APP'')
    rdoc.rdoc_files.include(''app/**/*.rb'')
    rdoc.rdoc_files.include(''lib/**/*.rb'')
    rdoc.rdoc_files.include(''vendor/plugins/**/*.rb'')
    rdoc.rdoc_files.include(''test/**/*.rb'')
    rdoc.rdoc_files.exclude(''lib/tasks/*'')
  end
end

I''m no Rake or RDoc wizard. I tried running rake --trace doc:custom,
but the
results didn''t seem to tell me anything: 
** Invoke doc:custom (first_time)
** Invoke doc/app/index.html (first_time)
** Invoke doc/README_FOR_APP (first_time, not_needed)
... # ''Invokes'' for every file, followed by
''(first_time, not_needed)''.
** Execute doc/app/index.html
rm -r doc/app
... # lists out all the files...
Generating HTML...
Files:   132
Classes: 173
Modules: 19
Methods: 1181
Elapsed: 52.921s
rm -r doc/app
... # lists out all the files...
Generating HTML...
Files:   251
Classes: 287
Modules: 97
Methods: 1854
Elapsed: 106.524s
** Execute doc:custom

Does the execute doc/app/index.html build all the doc, and then Execute
doc:custom do it again?

Before I dig into the internals of Rake, anyone have any ideas on
what''s going
on? Thanks.