BUG: label_vertebrae: fixed issue #508
BUG: label_vertebrae: fixed issue #508

Former-commit-id: 7e6f0a2ffe1209f067a1f819507f66b0d750f607
Former-commit-id: 039055efb484c573d45932cb57ddf13b93a373ba
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox