For example runUnitTest in ERP5 runs test program with $PATH set without those
directores. This leads to failures like

      File "/srv/slapgrid/slappart16/srv/testnode/djk/soft/950bed0366ff018b829e9bbb7dc3326f/parts/wendelin.core/wcfs/__init__.py", line 533, in _is_mountpoint
        mounted = (0 == subprocess.call(["mountpoint", "-q", path]))
      File "/srv/slapgrid/slappart16/srv/testnode/djk/shared/python2.7/a8bdae732e550b385eb04a06ed09d383/lib/python2.7/subprocess.py", line 172, in call
        return Popen(*popenargs, **kwargs).wait()
      File "/srv/slapgrid/slappart16/srv/testnode/djk/shared/python2.7/a8bdae732e550b385eb04a06ed09d383/lib/python2.7/subprocess.py", line 394, in __init__
        errread, errwrite)
      File "/srv/slapgrid/slappart16/srv/testnode/djk/shared/python2.7/a8bdae732e550b385eb04a06ed09d383/lib/python2.7/subprocess.py", line 1047, in _execute_child
        raise child_exception
    OSError: [Errno 2] No such file or directory

where those system programs are not found.