Use CHROMEOS_VERSION_PATCH=200912221142 for developer builds for use by the auto-updater.

src/scripts/chromeos_version.sh

 #!/bin/sh
 
 # 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.
 
 # ChromeOS version information
 #
 # This file is usually sourced by other build scripts, but can be run 
 # directly to see what it would do.
@@ skipping 55 matching lines @@
   # Developer hand-builds
   # Sets the codename to the user who built the image. This
   # will help us figure out who did the build if a different
   # person is debugging the system.
   export CHROMEOS_VERSION_CODENAME="$USER"
 
   export CHROMEOS_VERSION_NAME="Chromium OS"
   export CHROMEOS_VERSION_TRACK="developer-build"
   export CHROMEOS_VERSION_AUSERVER="http://$HOSTNAME:8080/update"
   export CHROMEOS_VERSION_DEVSERVER="http://$HOSTNAME:8080"
+  # Overwrite CHROMEOS_VERSION_PATCH with a date string for use by auto-updater
+  export CHROMEOS_VERSION_PATCH=$(date +%Y%m%d%H%M)
 fi
 
 # Version string. Not indentied to appease bash.
 export CHROMEOS_VERSION_STRING=\
 "${CHROMEOS_VERSION_MAJOR}.${CHROMEOS_VERSION_MINOR}"\
 ".${CHROMEOS_VERSION_BRANCH}.${CHROMEOS_VERSION_PATCH}"
 
 # Print version info.
 echo "ChromeOS version information:"
 env | egrep "^CHROMEOS_VERSION" | sed 's/^/    /'