Modify to work with cros_workon.

devserver.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.
 
 import autoupdate
 import buildutil
 import optparse
 import os
 import sys
 import web
@@ skipping 19 matching lines @@
     builds the package specified by the pkg parameter and returns the name
     of the output file.
   """
   def POST(self):
     input = web.input()
     web.debug('emerging %s ' % input.pkg)
     emerge_command = 'emerge-%s %s' % (input.board, input.pkg)
     err = os.system(emerge_command)
     if err != 0:
       raise Exception('failed to execute %s' % emerge_command)
+    eclean_command = 'eclean-%s -d packages' % input.board
+    err = os.system(eclean_command)
+    if err != 0:
+      raise Exception('failed to execute %s' % emerge_command)
 
 def OverrideWSGIServer(server_address, wsgi_app):
   """Creates a CherryPyWSGIServer instance.
 
   Overrides web.py's WSGIServer routine (web.httpserver.WSGIServer) to
   increase the accepted connection socket timeout from the default 10
   seconds to 10 minutes. The extra time is necessary to serve delta
   updates as well as update requests from a low priority update_engine
   process running on a heavily loaded Chrome OS device.
   """
@@ skipping 64 matching lines @@
   urls = ('/', 'index',
           '/update', 'update',
           '/update/(.+)', 'update',
           '/build', 'build')
 
   # Overrides the default WSGIServer routine -- see OverrideWSGIServer.
   web.httpserver.WSGIServer = OverrideWSGIServer
   app = web.application(urls, globals(), autoreload=True)
   render = web.template.render('templates/')
   app.run()