debug: when new raw source comes update the original reference

fixes #42139

src/vs/workbench/parts/debug/common/debugModel.ts

@@ -560,6 +560,7 @@ export class Process implements IProcess {
 		let source = new Source(raw, this.getId());
 		if (this.sources.has(source.uri.toString())) {
 			source = this.sources.get(source.uri.toString());
+			source.raw = raw;
 		} else {
 			this.sources.set(source.uri.toString(), source);
 		}

src/vs/workbench/parts/debug/common/debugSource.ts

@@ -19,7 +19,7 @@ export class Source {
 	public readonly uri: uri;
 	public available: boolean;
 
-	constructor(public readonly raw: DebugProtocol.Source, sessionId: string) {
+	constructor(public raw: DebugProtocol.Source, sessionId: string) {
 		if (!raw) {
 			this.raw = { name: UNKNOWN_SOURCE_LABEL };
 		}
@@ -110,4 +110,4 @@ export class Source {
 			processId
 		};
 	}
-}
\ No newline at end of file
+}