Adds support for autoupdating portage with portage images

src/platform/dev/autoupdate.py

 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from buildutil import BuildObject
 from xml.dom import minidom
 
 import os
 import web
 
@@ skipping 29 matching lines @@
       </gupdate>
     """
     return payload % self.app_id
 
   def GetLatestImagePath(self):
     cmd = "%s/get_latest_image.sh" % self.scripts_dir
     return os.popen(cmd).read().strip()
 
   def GetLatestVersion(self, latest_image_path):
     latest_version = latest_image_path.split('/')[-1]
+
+    # Removes the portage build prefix.
+    latest_version = latest_version.lstrip("g-")
     return latest_version.split('-')[0]
 
   def CanUpdate(self, client_version, latest_version):
     """
       Returns true iff the latest_version is greater than the client_version.
     """
     client_tokens = client_version.split('.')
     latest_tokens = latest_version.split('.')
     web.debug("client version %s latest version %s" % (client_version, latest_version))
     for i in range(0,4):
@@ skipping 44 matching lines @@
     if ok != True:
       web.debug("Failed to build an update image")
       return self.GetNoUpdatePayload()
 
     hash = self.GetHash("%s/update.gz" % self.static_dir)
     size = self.GetSize("%s/update.gz" % self.static_dir)
     hostname = web.ctx.host
     url = "http://%s/static/update.gz" % hostname
     return self.GetUpdatePayload(hash, size, url)