OPT: label_vertebrae: fixed adjustment of mirrored pattern
OPT: label_vertebrae: fixed adjustment of mirrored pattern

Former-commit-id: 0c9315d46cdb311b972727490365144894b57d31 [formerly 7380dfb2dfd0d6089ab87c2b62cbc96476440595]
Former-commit-id: 1354f4c74afeff579f9ab5adfaf0d4cc434e86e0
Former-commit-id: 9c7204d3ac576451b6984415e6bc929fa9b4e60b
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox