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

utils/pub/pub.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.
 
 /// The main entrypoint for the pub command line application.
 library pub;
 
 import 'dart:async';
 import '../../pkg/args/lib/args.dart';
 import '../../pkg/path/lib/path.dart' as path;
 import 'dart:io';
 import 'dart:math';
 import 'http.dart';
 import 'io.dart';
 import 'command_help.dart';
 import 'command_install.dart';
 import 'command_lish.dart';
 import 'command_update.dart';
 import 'command_uploader.dart';
 import 'command_version.dart';
 import 'entrypoint.dart';
 import 'exit_codes.dart' as exit_codes;
 import 'log.dart' as log;
 import 'package.dart';
 import 'pubspec.dart';
+import 'sdk.dart' as sdk;
 import 'source.dart';
 import 'source_registry.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 import 'version.dart';
 
-Version get pubVersion => new Version(0, 0, 0);
-
 /// The commands that Pub understands.
 Map<String, PubCommand> get pubCommands {
   var commands = {
     'help': new HelpCommand(),
     'install': new InstallCommand(),
     'publish': new LishCommand(),
     'update': new UpdateCommand(),
     'uploader': new UploaderCommand(),
     'version': new VersionCommand()
   };
@@ skipping 121 matching lines @@
     buffer.add('  ${padRight(name, length)}   '
         '${pubCommands[name].description}\n');
   }
 
   buffer.add('\n');
   buffer.add('Use "pub help [command]" for more information about a command.');
   log.message(buffer.toString());
 }
 
 void printVersion() {
-  log.message('Pub $pubVersion');
+  log.message('Pub ${sdk.version}');
 }
 
 abstract class PubCommand {
   SystemCache cache;
   ArgResults globalOptions;
   ArgResults commandOptions;
 
   Entrypoint entrypoint;
 
   /// A one-line description of this command.
@@ skipping 116 matching lines @@
     if (exception is HttpException || exception is HttpParserException ||
         exception is SocketIOException || exception is PubHttpException) {
       return exit_codes.UNAVAILABLE;
     } else if (exception is FormatException) {
       return exit_codes.DATA;
     } else {
       return 1;
     }
   }
 }