sct_flatten_sagittal: pass env
sct_flatten_sagittal: pass env


Former-commit-id: a8020175f7df525dbcc8fc5d38adab60fe1accda
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox