I just tested a script in Rhino 6 Beta + Grasshopper 1.0 and the patch command gave me the exterior of the patch, not the interior
Rhino 5.0 or Rhino 6 patch command give the good result.
The initial GH is here which worked in RH5/G0.9
Yup, logged as RH-42596.
RH-42596 is fixed in the latest BETA