Gracefully handle a missing locked version in pub get.

sdk/lib/_internal/pub/test/get/hosted/unlock_if_version_doesnt_exist_test.dart

Index: sdk/lib/_internal/pub/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
diff --git a/sdk/lib/_internal/pub/test/get/hosted/unlock_if_incompatible_test.dart b/sdk/lib/_internal/pub/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
similarity index 54%
copy from sdk/lib/_internal/pub/test/get/hosted/unlock_if_incompatible_test.dart
copy to sdk/lib/_internal/pub/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
index 4621703ce71d3cc91b72be0523209edd0e262bbf..2b662e669fed46223947fff8c74fe7a9db58988a 100644
--- a/sdk/lib/_internal/pub/test/get/hosted/unlock_if_incompatible_test.dart
+++ b/sdk/lib/_internal/pub/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
@@ -1,28 +1,30 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../../../lib/src/io.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   initConfig();
-  integration('upgrades a locked pub server package with a new incompatible '
-      'constraint', () {
+  integration('upgrades a locked pub server package with a nonexistent version',
+      () {
     servePackages([packageMap("foo", "1.0.0")]);
 
     d.appDir({"foo": "any"}).create();
-
     pubGet();
-
     d.packagesDir({"foo": "1.0.0"}).validate();
-    servePackages([packageMap("foo", "1.0.1")]);
-    d.appDir({"foo": ">1.0.0"}).create();
 
-    pubGet();
+    schedule(() => deleteEntry(p.join(sandboxDir, cachePath)));
 
+    servePackages([packageMap("foo", "1.0.1")], replace: true);
+    pubGet();
     d.packagesDir({"foo": "1.0.1"}).validate();
   });
 }