BUG: correct size of mask with new sct_create_mask
BUG: correct size of mask with new sct_create_mask

Former-commit-id: 64417fc4b83bc96a4c6f13787b80f640b4b32fac
Former-commit-id: e7b8a6efa9794e9640527c9d64a6c78c63d9d8c4
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox