- Added another flag to P_FindFloorCeiling() to get it to do its standard processing but

without resetting the actor's sector. The 3D floor checks in P_NightmareRespawn() and
  A_RestoreSpecialPosition now use this.
- Fixed: P_NightmareRespawn() did its Z clamping before checking for 3D floors.
- Fixed: Respawning actors were not clamped to the ceiling.

SVN r3542 (trunk)

src/thingdef/thingdef_codeptr.cpp

@@ -2697,7 +2697,7 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_Respawn)
 			self->dropoffz =
 			self->floorz = sec->floorplane.ZatPoint(self->x, self->y);
 			self->ceilingz = sec->ceilingplane.ZatPoint(self->x, self->y);
-			P_FindFloorCeiling(self, true);
+			P_FindFloorCeiling(self, FFCF_ONLYSPAWNPOS);
 		}
 	}
 	else