Incorrect error ".../setuptools-0.6c11-py2.5.egg-info already exists and does not belong to a registered port"

[vinc17@…]

When trying to upgrade py25-numpy:

--->  Computing dependencies for py25-nose..
--->  Dependencies to be installed: py25-distribute
--->  Activating py25-distribute @0.6.13_0
Error: Target org.macports.activate returned: Image error: /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info already exists and does not belong to a registered port.  Unable to activate port py25-distribute. Use 'port -f activate py25-distribute' to force the activation.
Log for py25-distribute is at: /opt/local/var/macports/logs/_Users_vinc17_software_dports_python_py25-distribute/main.log
Error: The following dependencies failed to build: py25-distribute
Error: Unable to upgrade port: 1

However /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info has files that belong to py25-setuptools:

$ port contents py25-setuptools | grep /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/PKG-INFO
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/SOURCES.txt
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/dependency_links.txt
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/entry_points.txt
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/top_level.txt
  /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info/zip-safe

and all the files in /opt/local/lib/python2.5/site-packages/setuptools-0.6c11-py2.5.egg-info belong to py25-setuptools.

So either there should be no errors or the activation of py25-distribute tries to remove files from py25-setuptools, contrary to what the message says, and using -f as suggested may break the installation!