Bring in the latest pub.

DEPS

 # 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.
 
 vars = {
   # The dart_root is the root of our sdk checkout. This is normally
   # simply sdk, but if using special gclient specs it can be different.
   "dart_root": "sdk",
 
   # We use mirrors of all github repos to guarantee reproducibility and
@@ skipping 49 matching lines @@
   "mime_rev": "@75890811d4af5af080351ba8a2853ad4c8df98dd",
   "mustache4dart_rev" : "@5724cfd85151e5b6b53ddcd3380daf188fe47f92",
   "oauth2_tag": "@1.0.0",
   "observe_rev": "@eee2b8ec34236fa46982575fbccff84f61202ac6",
   "observatory_pub_packages_rev": "@cf90eb9077177d3d6b3fd5e8289477c2385c026a",
   "package_config_rev": "@0.1.3",
   "path_tag": "@1.3.6",
   "ply_rev": "@604b32590ffad5cbb82e4afef1d305512d06ae93",
   "plugin_tag": "@0.1.0",
   "pool_tag": "@1.2.1",
-  "pub_rev": "@a1dd3484795b2bc221aaa8d007f3162251b3c08e",
+  "pub_rev": "@57a17f2567d1ff3325960d0960f939fa243b5fd7",
   "pub_cache_tag": "@v0.1.0",
   "pub_semver_tag": "@1.2.1",
   "quiver_tag": "@0.21.4",
   "root_certificates_rev": "@c3a41df63afacec62fcb8135196177e35fe72f71",
   "scheduled_test_tag": "@0.12.4+2",
   "shelf_tag": "@0.6.4+3",
   "smoke_rev" : "@f3361191cc2a85ebc1e4d4c33aec672d7915aba9",
   "source_maps_tag": "@0.10.1",
   "shelf_static_tag": "@0.2.3+1",
   "shelf_web_socket_tag": "@0.0.1+4",
@@ skipping 340 matching lines @@
       "--no_resume",
       "--bucket",
       "dart-dependencies",
       "--platform=linux*",
       "--extract",
       "-s",
       Var('dart_root') + "/third_party/clang.tar.gz.sha1",
     ],
   },
 ]