'virtualenv -p python3 /tmp/xx' should work but doesn't

Binary package hint: python-virtualenv

From the Debian bug report:

$ virtualenv -p python3 /tmp/xx

but it fails with this traceback:

-----snip snip-----
Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/virtualenv.py", line 1892, in <module>
    main()
  File "/usr/lib/python2.6/dist-packages/virtualenv.py", line 753, in main
    prompt=options.prompt)
  File "/usr/lib/python2.6/dist-packages/virtualenv.py", line 851, in create_environment
    install_distribute(py_executable, unzip=unzip_setuptools)
  File "/usr/lib/python2.6/dist-packages/virtualenv.py", line 575, in install_distribute
    _install_req(py_executable, unzip, distribute=True)
  File "/usr/lib/python2.6/dist-packages/virtualenv.py", line 474, in _install_req
    import pkg_resources
  File "/usr/share/pyshared/pkg_resources.py", line 45
    def _bypass_ensure_directory(name, mode=0777):
                                               ^
SyntaxError: invalid token