bugfix: ds9 regions would misbehave, possibly wrapping or adopting negative indices incorrectly, if the entire region is outside the image
bugfix: ds9 regions would misbehave, possibly wrapping or adopting
negative indices incorrectly, if the entire region is outside the image

keflavich/spectral-cube,low-sky/spectral-cube,e-koch/spectral-cube,radio-astro-tools/spectral-cube,jzuhone/spectral-cube