Fix getDefaultVariantNode for UM2

CURA-5790

UM2 has optional variant which depends on whether Olsson Block is
enabled. getDefaultVariantNode() should take that into account.

cura/Machines/VariantManager.py

@@ -115,17 +115,24 @@ class VariantManager:
 
     #
     # Gets the default variant for the given machine definition.
+    # If the optional GlobalStack is given, the metadata information will be fetched from the GlobalStack instead of
+    # the DefinitionContainer. Because for machines such as UM2, you can enable Olsson Block, which will set
+    # "has_variants" to True in the GlobalStack. In those cases, we need to fetch metadata from the GlobalStack or
+    # it may not be correct.
     #
     def getDefaultVariantNode(self, machine_definition: "DefinitionContainer",
-                              variant_type: VariantType) -> Optional["ContainerNode"]:
+                              variant_type: "VariantType",
+                              global_stack: Optional["GlobalStack"] = None) -> Optional["ContainerNode"]:
         machine_definition_id = machine_definition.getId()
+        container_for_metadata_fetching = global_stack if global_stack is not None else machine_definition
+
         preferred_variant_name = None
         if variant_type == VariantType.BUILD_PLATE:
-            if parseBool(machine_definition.getMetaDataEntry("has_variant_buildplates", False)):
-                preferred_variant_name = machine_definition.getMetaDataEntry("preferred_variant_buildplate_name")
+            if parseBool(container_for_metadata_fetching.getMetaDataEntry("has_variant_buildplates", False)):
+                preferred_variant_name = container_for_metadata_fetching.getMetaDataEntry("preferred_variant_buildplate_name")
         else:
-            if parseBool(machine_definition.getMetaDataEntry("has_variants", False)):
-                preferred_variant_name = machine_definition.getMetaDataEntry("preferred_variant_name")
+            if parseBool(container_for_metadata_fetching.getMetaDataEntry("has_variants", False)):
+                preferred_variant_name = container_for_metadata_fetching.getMetaDataEntry("preferred_variant_name")
 
         node = None
         if preferred_variant_name:

cura/Settings/CuraStackBuilder.py

@@ -114,7 +114,8 @@ class CuraStackBuilder:
 
         # get variant container for extruders
         extruder_variant_container = application.empty_variant_container
-        extruder_variant_node = variant_manager.getDefaultVariantNode(global_stack.definition, VariantType.NOZZLE)
+        extruder_variant_node = variant_manager.getDefaultVariantNode(global_stack.definition, VariantType.NOZZLE,
+                                                                      global_stack = global_stack)
         extruder_variant_name = None
         if extruder_variant_node:
             extruder_variant_container = extruder_variant_node.getContainer()

resources/definitions/ultimaker2.def.json

@@ -14,6 +14,7 @@
         "platform_offset": [9, 0, 0],
         "has_materials": false,
         "has_machine_quality": true,
+        "preferred_variant_name": "0.4 mm",
         "exclude_materials": ["generic_hips", "generic_petg", "generic_bam", "ultimaker_bam", "generic_pva", "ultimaker_pva", "generic_tough_pla", "ultimaker_tough_pla_black", "ultimaker_tough_pla_green", "ultimaker_tough_pla_red", "ultimaker_tough_pla_white"],
         "first_start_actions": ["UM2UpgradeSelection"],
         "supported_actions":["UM2UpgradeSelection", "UpgradeFirmware"],