handle edge case, fixes #11402

src/vs/workbench/api/node/extHostWorkspace.ts

@@ -39,7 +39,7 @@ export class ExtHostWorkspace {
 		}
 
 		if (isEqualOrParent(path, this._workspacePath)) {
-			return relative(this._workspacePath, path);
+			return relative(this._workspacePath, path) || path;
 		}
 
 		return path;

src/vs/workbench/test/node/api/extHostWorkspace.test.ts

@@ -20,4 +20,16 @@ suite('ExtHostWorkspace', function () {
 			'm:/Apps/DartPubCache/hosted/pub.dartlang.org/convert-2.0.1/lib/src/hex.dart');
 
 	});
+
+	test('asRelativePath, same paths, #11402', function () {
+		const root = '/home/aeschli/workspaces/samples/docker';
+		const input = '/home/aeschli/workspaces/samples/docker';
+		const ws = new ExtHostWorkspace(new TestThreadService(), root);
+
+		assert.equal(ws.getRelativePath(input), input);
+
+		const input2 = '/home/aeschli/workspaces/samples/docker/a.file';
+		assert.equal(ws.getRelativePath(input2), 'a.file');
+
+	});
 });