prefix option in install.py not needed

parser.add_argument("-v", "--version", required=True,

                    help="path to the LAMMPS version.h header file")

pgroup = parser.add_mutually_exclusive_group()

pgroup.add_argument("-d","--dir",

                    help="Legacy custom installation folder for module and library")

pgroup.add_argument("-p","--prefix",

                    help="Installation prefix for module and library")

parser.add_argument("-d","--dir",

                    help="Legacy custom installation folder selection for module and library")

args = parser.parse_args()

  else:

    args.dir = os.path.abspath(args.dir)

if args.prefix:

  if not os.path.isdir(args.prefix):

    print( "ERROR: Installation prefix folder %s does not exist" % args.prefix)

    parser.print_help()

    sys.exit(1)

  else:

    args.prefix = os.path.abspath(args.prefix)

# if a custom directory is given, we copy the files directly

# without any special processing or additional steps to that folder

tryuser=False

try:

  if args.prefix:

    sys.argv = ["setup.py","install","--prefix=%s" % args.prefix]    # as if had run "python setup.py install --prefix=XXX"

  else:

  sys.argv = ["setup.py","install"]    # as if had run "python setup.py install"

  setup(name = "lammps",

        version = verstr,

        description = "LAMMPS Molecular Dynamics Python module",

        license = "GPL",

        py_modules = ["lammps"],

        data_files = [(get_python_lib(prefix=args.prefix), [args.lib])])

        data_files = [(get_python_lib(), [args.lib])])

except:

  tryuser=True

  print ("Installation into global site-packages folder failed.\nTrying user folder %s now." % site.USER_SITE)