run.command(): Add check for mrconvert_keyval erroneous quoting
run.command(): Add check for mrconvert_keyval erroneous quoting

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