Don't wipe cache dir, only its contents.

devserver.py

 #!/usr/bin/python
 
 # Copyright (c) 2009-2010 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.
 
 """A CherryPy-based webserver to host images and build packages."""
 
 import cherrypy
 import optparse
@@ skipping 147 matching lines @@
     static_dir = os.path.realpath(options.archive_dir)
     _PrepareToServeUpdatesOnly(static_dir)
     serve_only = True
   else:
     static_dir = os.path.realpath('%s/static' % devserver_dir)
     os.system('mkdir -p %s' % static_dir)
 
   cache_dir = os.path.join(static_dir, 'cache')
   cherrypy.log('Using cache directory %s' % cache_dir, 'DEVSERVER')
 
-  if options.clear_cache:
-    # Clear the cache and exit on error
-    if os.system('sudo rm -rf %s' % cache_dir) != 0:
-      cherrypy.log('Failed to clear the cache with %s' % cmd,
-                   'DEVSERVER')
-      sys.exit(1)
+  if os.path.exists(cache_dir):
+    if options.clear_cache:
+      # Clear the cache and exit on error.
+      if os.system('rm -rf %s/*' % cache_dir) != 0:
+        cherrypy.log('Failed to clear the cache with %s' % cmd,
+                     'DEVSERVER')
+        sys.exit(1)
 
-  if os.path.exists(cache_dir):
-    # Clear all but the last N cached updates
-    cmd = ('cd %s; ls -tr | head --lines=-%d | xargs rm -rf' %
-           (cache_dir, CACHED_ENTRIES))
-    if os.system(cmd) != 0:
-      cherrypy.log('Failed to clean up old delta cache files with %s' % cmd,
-                   'DEVSERVER')
-      sys.exit(1)
+    else:
+      # Clear all but the last N cached updates
+      cmd = ('cd %s; ls -tr | head --lines=-%d | xargs rm -rf' %
+             (cache_dir, CACHED_ENTRIES))
+      if os.system(cmd) != 0:
+        cherrypy.log('Failed to clean up old delta cache files with %s' % cmd,
+                     'DEVSERVER')
+        sys.exit(1)
+  else:
+    os.makedirs(cache_dir)
 
   cherrypy.log('Source root is %s' % root_dir, 'DEVSERVER')
   cherrypy.log('Serving from %s' % static_dir, 'DEVSERVER')
 
   updater = autoupdate.Autoupdate(
       root_dir=root_dir,
       static_dir=static_dir,
       serve_only=serve_only,
       urlbase=options.urlbase,
       test_image=options.test_image,
@@ skipping 18 matching lines @@
     # We don't run the dev server with this option.
     if options.validate_factory_config:
       sys.exit(0)
   elif options.pregenerate_update:
     if not updater.PreGenerateUpdate():
       sys.exit(1)
 
   # If the command line requested after setup, it's time to do it.
   if not options.exit:
     cherrypy.quickstart(DevServerRoot(), config=_GetConfig(options))