easy_install.py _get_version fails if executable is missing

[Adam Groszer]

Having this buildout.cfg snippet:

[unopython]
executable = /usr/bin/python

[pyuno-ctl]
recipe = zc.recipe.egg
eggs = ulif.openoffice
scripts = pyunoctl convert
python = unopython

If /usr/bin/python is missing, easy_install.py def _get_version(executable) fails with:
Traceback (most recent call last):
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\buildout.py", line 1683, in main
    getattr(buildout, command)(args)
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\buildout.py", line 555, in install
    installed_files = self[part]._call(recipe.install)
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\buildout.py", line 1227, in _call
    return f()
  File "u:\eggs\zc.recipe.egg-1.2.2-py2.6.egg\zc\recipe\egg\egg.py", line 132, in install
    reqs, ws = self.working_set()
  File "u:\eggs\zc.recipe.egg-1.2.2-py2.6.egg\zc\recipe\egg\egg.py", line 90, in working_set
    **kw)
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\easy_install.py", line 799, in install
    allow_hosts=allow_hosts)
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\easy_install.py", line 195, in __init__
    python=_get_version(executable))
  File "u:\eggs\zc.buildout-1.4.4-py2.6.egg\zc\buildout\easy_install.py", line 91, in _get_version
    pystring, version = version.split()
ValueError: too many values to unpack

because version == "The system cannot find the path specified." (well, on windows)