Fix of https://github.com/prusa3d/Slic3r/issues/492 When a layer contained the support interface only, it was errorneously printed with the support base material.
Fix of https://github.com/prusa3d/Slic3r/issues/492
When a layer contained the support interface only, it was errorneously
printed with the support base material.

prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r