Bump pub to the latest version.

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",
 
   # The svn location to pull out dependencies from
@@ skipping 68 matching lines @@
   "nss_rev": "@87b96db4268293187d7cf741907a6d5d1d8080e0",
   "oauth2_rev": "@1bff41f4d54505c36f2d1a001b83b8b745c452f5",
   "observe_rev": "@eee2b8ec34236fa46982575fbccff84f61202ac6",
   "observatory_pub_packages_rev": "@cdc4b3d4c15b9c0c8e7702dff127b440afbb7485",
   "package_config_rev": "@0.1.3",
   "path_tag": "@1.3.6",
   "petitparser_rev" : "@37878",
   "ply_rev": "@604b32590ffad5cbb82e4afef1d305512d06ae93",
   "plugin_tag": "@0.1.0",
   "pool_rev": "@e454b4b54d2987e8d2f0fbd3ac519641ada9bd0f",
-  "pub_rev": "@d90268693d1a9dbe5ea11cd9c80b842e3bf1581c",
+  "pub_rev": "@5b06b469abafcf6ab7ef0b6dccf4d50e971ae258",
   "pub_cache_tag": "@v0.1.0",
   "pub_semver_tag": "@1.2.1",
   "quiver_tag": "@0.21.4",
   "root_certificates_rev": "@c3a41df63afacec62fcb8135196177e35fe72f71",
   "scheduled_test_tag": "@0.12.1+2",
   "shelf_rev": "@1e87b79b21ac5e6fa2f93576d6c06eaa65285ef4",
   "smoke_rev" : "@f3361191cc2a85ebc1e4d4c33aec672d7915aba9",
   "source_maps_tag": "@0.10.1",
   "sqlite_rev": "@38811b79f42801662adc0458a25270ab690a6b81",
   "shelf_static_rev": "@v0.2.1",
@@ skipping 299 matching lines @@
       "--bucket",
       "dart-dependencies",
       "--recursive",
       "--auto_platform",
       "--extract",
       "--directory",
       Var('dart_root') + "/tools/sdks",
     ],
   },
 ]