[phenixbb] assert n_ncs > 0

[Robert Ng]

Hi again,
How about this one ...
Traceback (most recent call last):
  File "/usr/local/phenix-1.6.1-348/phenix/phenix/command_line/refine.py",
line 11, in <module>
    command_line.run(command_name="phenix.refine", args=sys.argv[1:])
  File "/usr/local/phenix-1.6.1-348/phenix/phenix/refinement/command_line.py",
line 71, in run
    overwrite = command_line_interpreter.command_line.options.overwrite)
  File "/usr/local/phenix-1.6.1-348/phenix/phenix/refinement/driver.py",
line 413, in __init__
    self.process_ncs_restraint_groups()
  File "/usr/local/phenix-1.6.1-348/phenix/phenix/refinement/driver.py",
line 672, in process_ncs_restraint_groups
    log = log)
  File "/usr/local/phenix-1.6.1-348/cctbx_project/mmtbx/ncs/restraints.py",
line 306, in from_atom_selections
    log=log)
  File "/usr/local/phenix-1.6.1-348/cctbx_project/mmtbx/ncs/restraints.py",
line 219, in __init__
    assert n_ncs > 0
AssertionError

Thanks again,
Robert