fix potential netcdf bug
fix potential netcdf bug

choderalab/openpathsampling,openpathsampling/openpathsampling,jhprinz/openpathsampling,choderalab/openpathsampling,jhprinz/openpathsampling,openpathsampling/openpathsampling,dwhswenson/openpathsampling,openpathsampling/openpathsampling,openpathsampling/openpathsampling,dwhswenson/openpathsampling,dwhswenson/openpathsampling,choderalab/openpathsampling,dwhswenson/openpathsampling,jhprinz/openpathsampling