fix (again) microsoft#133210

Author: jrieken

src/vs/workbench/services/decorations/browser/decorationsService.ts

@@ -263,7 +263,7 @@ export class DecorationsService implements IDecorationsService {
 	}
 
 	registerDecorationsProvider(provider: IDecorationsProvider): IDisposable {
-		const rm = this._provider.push(provider);
+		const rm = this._provider.unshift(provider);
 
 		this._onDidChangeDecorations.fire({
 			// everything might have changed

src/vs/workbench/services/decorations/test/browser/decorationsService.test.ts

@@ -300,4 +300,31 @@ suite('DecorationsService', function () {
 			emitter.fire([uri]);
 		});
 	});
+
+	test('FileDecorationProvider intermittently fails #133210', async function () {
+
+		const invokeOrder: string[] = [];
+
+		service.registerDecorationsProvider(new class {
+			label = 'Provider-1';
+			onDidChange = Event.None;
+			provideDecorations() {
+				invokeOrder.push(this.label);
+				return undefined;
+			}
+		});
+
+		service.registerDecorationsProvider(new class {
+			label = 'Provider-2';
+			onDidChange = Event.None;
+			provideDecorations() {
+				invokeOrder.push(this.label);
+				return undefined;
+			}
+		});
+
+		service.getDecoration(URI.parse('test://me/path'), false);
+
+		assert.deepStrictEqual(invokeOrder, ['Provider-2', 'Provider-1']);
+	});
 });