Spurious warning if setup.py specifies install_requires=['distribute']

When using zc.buildout with Distribute, if you use "install_requires=['distribute']" in your setup.py file, as per http://packages.python.org/distribute/using.html, then zc.buildout prints a spurious warning. The buildout still succeeds, but zc.buildout prints the following warning to the console:

Develop distribution: foo 1.0beta1
uses namespace packages but the distribution does not require setuptools.
Generated script '/home/mars/src/foo/bin/tags'.

You can work around this issue by adding 'setuptools' to the install_requires stanza like so:

  install_requires=[
    'distribute',
    'setuptools', # Redundant, removes warning
  ]

Seen in zc.buildout 1.5.0b1.