Make pub use the SDK's "version" file for its version.

utils/tests/pub/install/sdk/check_out_test.dart

 // Copyright (c) 2012, 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 'dart:io';
 
 import '../../test_pub.dart';
 
 main() {
   integration('checks out a package from the SDK', () {
     dir(sdkPath, [
-      file('revision', '1234'),
+      file('version', '0.1.2.3'),
       dir('pkg', [
         dir('foo', [
-          libDir('foo', 'foo 0.0.1234'),
+          libDir('foo', 'foo 0.1.2+3'),
           libPubspec('foo', '0.0.0-not.used')
         ])
       ])
     ]).scheduleCreate();
 
     dir(appPath, [
       pubspec({"name": "myapp", "dependencies": {"foo": {"sdk": "foo"}}})
     ]).scheduleCreate();
 
     schedulePub(args: ['install'],
         output: new RegExp(r"Dependencies installed!$"));
 
-    packagesDir({"foo": "0.0.1234"}).scheduleValidate();
+    packagesDir({"foo": "0.1.2+3"}).scheduleValidate();
   });
 }