Fix old cached updateChannel default being used after package.json modification. (#8032)

* Fix old cached extension being used after package.json modification.
* Limit it to when updateChannel is changed.

Author: sean-mcmanus

Extension/src/main.ts

@@ -460,15 +460,23 @@ function rewriteManifest(): Promise<void> {
         "onFileSystem:cpptools-schema"
     ];
 
+    let doTouchExtension: boolean = false;
+
     const packageJsonPath: string = util.getExtensionFilePath("package.json");
     if (packageJsonPath.includes(".vscode-insiders") ||
         packageJsonPath.includes(".vscode-server-insiders") ||
         packageJsonPath.includes(".vscode-exploration") ||
         packageJsonPath.includes(".vscode-server-exploration")) {
         if (packageJson.contributes.configuration.properties['C_Cpp.updateChannel'].default === 'Default') {
             packageJson.contributes.configuration.properties['C_Cpp.updateChannel'].default = 'Insiders';
+            doTouchExtension = true;
         }
     }
 
-    return util.writeFileText(util.getPackageJsonPath(), util.stringifyPackageJson(packageJson));
+    return util.writeFileText(util.getPackageJsonPath(), util.stringifyPackageJson(packageJson)).then(() => {
+        if (doTouchExtension) {
+            // This is required to prevent VS Code from using the cached version with the old updateChannel setting.
+            util.touchExtensionFolder();
+        }
+    });
 }