warning when b-value scaling is used for b-zero.
warning when b-value scaling is used for b-zero.

The code detects ambiguous entries of the form [ 0 0 0 non-zero ],
and triggers a warning when these are by rescaled to b=0 scans.

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3