BUG: keep same volume when cropping with an uncomplete segmentation. Fix #879
BUG: keep same volume when cropping with an uncomplete segmentation. Fix #879

3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox