Remove need to explicitly clear widget mapping variable when invoking overridden widget

core/modules/widgets/ubertransclude.js

@@ -88,8 +88,15 @@ UberTranscludeWidget.prototype.execute = function() {
 			});
 	}
 	var parseTreeNodes = parser ? parser.tree : (this.slotValueParseTrees["missing"] || []);
-	this.sourceText = parser ? parser.source : null;
-	this.parserType = parser? parser.type : null;
+	this.sourceText = parser ? parser.source : undefined;
+	this.parserType = parser? parser.type : undefined;
+	// Wrap the transcluded content if required
+	if(this.slotValueParseTrees["wrapper"]) {
+		this.slotValueParseTrees["wrapped"] = parseTreeNodes;
+		parseTreeNodes = this.slotValueParseTrees["wrapper"];
+		this.sourceTest = undefined;
+		this.sourceType = undefined;
+	}
 	// Set context variables for recursion detection
 	var recursionMarker = this.makeRecursionMarker();
 	if(this.recursionMarker === "yes") {

core/modules/widgets/widget.js

@@ -406,6 +406,32 @@ Widget.prototype.makeChildWidget = function(parseTreeNode,options) {
 						"$name": {name: "$name", type: "string", value: "body"}
 					},
 					children: parseTreeNode.children
+				},
+				{
+					type: "value",
+					tag: "$value",
+					attributes: {
+						"$name": {name: "$name", type: "string", value: "wrapper"}
+					},
+					children: [
+						{
+							type: "setvariable",
+							tag: "$setvariable",
+							attributes: {
+								"name": {name: "name", type: "string", value: variableDefinitionName},
+								"value": {name: "value", type: "string", value: ""}
+							},
+							children: [
+								{
+									type: "slot",
+									tag: "$slot",
+									attributes: {
+										"$name": {name: "$name", type: "string", value: "wrapped"}
+									}
+								}
+							]
+						}
+					]
 				}
 			]
 		};

editions/test/tiddlers/tests/data/ubertransclusion/CustomWidget-TextWidgetOverride.tid

@@ -15,12 +15,10 @@ title: TiddlerOne
 <!-- Redefine the <$text> widget by defining a transcludable variable with that name -->
 <$set name="<$text>" value="""\whitespace trim
 	<$parameters text='Jaguar'>
-		<$set name="<$text>" value="">
-			<$text text=<<text>>/>
-			<$slot $name="body">
-				Whale
-			</$slot>
-		</$set>
+		<$text text=<<text>>/>
+		<$slot $name="body">
+			Whale
+		</$slot>
 	</$parameters>"""
 >
 	<$text text="Dingo">