BUG: propseg: fixed issue #673
BUG: propseg: fixed issue #673

Former-commit-id: fdeed938c40193bc9e084fa55df5869b7454a792
Former-commit-id: 696582894c7341371a70b7a2b19ab00c66933dcf
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox