Install before starting the server if the lockfile is out of date.

sdk/lib/_internal/pub/test/serve/installs_first_if_path_dependency_changed_test.dart

Index: sdk/lib/_internal/pub/test/serve/installs_first_if_path_dependency_changed_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/installs_first_if_path_dependency_changed_test.dart b/sdk/lib/_internal/pub/test/serve/installs_first_if_path_dependency_changed_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..0380a9aba247718a2ced3a1a7d6cddeb1acf2b1f
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/serve/installs_first_if_path_dependency_changed_test.dart
@@ -0,0 +1,43 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub_tests;
+
+import 'dart:io';
+import 'dart:json' as json;
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+
+main() {
+  initConfig();
+  integration("installs first if a path dependency's path doesn't match the "
+      "one in the lock file", () {
+    d.dir("foo-before", [
+      d.libPubspec("foo", "0.0.1"),
+      d.libDir("foo", "before")
+    ]).create();
+
+    d.dir("foo-after", [
+      d.libPubspec("foo", "0.0.1"),
+      d.libDir("foo", "after")
+    ]).create();
+
+    d.appDir({
+      "foo": {"path": "../foo-before"}
+    }).create();
+
+    pubInstall();
+
+    // Change the path in the pubspec.
+    d.appDir({
+      "foo": {"path": "../foo-after"}
+    }).create();
+
+    startPubServe(shouldInstallFirst: true);
+    requestShouldSucceed("packages/foo/foo.dart", 'main() => "after";');
+    endPubServe();
+  });
+}