Bug fix: The quick effect operators got broken a bit by the new material slot behavior.

* The operators now add new materials and assign them to the created material slots explicitly.

release/scripts/startup/bl_operators/object_quick_effects.py

@@ -163,8 +163,8 @@ class MakeSmoke(bpy.types.Operator):
         # create a volume material with a voxel data texture for the domain
         bpy.ops.object.material_slot_add({"object": obj})
 
-        mat = obj.material_slots[0].material
-        mat.name = "Smoke Domain Material"
+        mat = bpy.data.materials.new("Smoke Domain Material");
+        obj.material_slots[0].material = mat
         mat.type = 'VOLUME'
         mat.volume.density = 0
         mat.volume.density_scale = 5
@@ -274,9 +274,10 @@ class MakeFluid(bpy.types.Operator):
 
         # create a ray-transparent material for the domain
         bpy.ops.object.material_slot_add({"object": obj})
+        
+        mat = bpy.data.materials.new("Fluid Domain Material");
+        obj.material_slots[0].material = mat
 
-        mat = obj.material_slots[0].material
-        mat.name = "Fluid Domain Material"
         mat.specular_intensity = 1
         mat.specular_hardness = 100
         mat.use_transparency = True