Add conversion script to convert Butterfly board to 32bit.

Add conversion script to convert 2GB butterfly board to 32bit.

BUG=chrome-os-partner:13254
TEST=run update_chroot, verify butterfly upgraded

Change-Id: Ia6e834b727e70bfb27af9c81175b5df09ef56e2e
Reviewed-on: https://gerrit.chromium.org/gerrit/31777
Tested-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Shawn Nematbakhsh <shawnn@chromium.org>

chroot_version_hooks.d/46_64bit_convert_butterfly

@@ -0,0 +1,28 @@
+# Copyright (c) 2012 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.
+
+# This is meant to happen immediately after we update these boards
+# from 64bit to 32bit.  It moves the existing build root out of the
+# way and re-creates the build root.  The user must remove the copy
+# of the old build root manually if it is not needed.
+
+for board in butterfly; do
+  build="/build/${board}"
+  if [[ -d ${build} ]] ; then
+    case ${HOSTNAME:-$(hostname)} in
+    *.golo.chromium.org)
+      # Do not keep on buildbots.
+      sudo rm -rf "${build}"
+      ;;
+    *)
+      info "Moving 64bit ${board} to ${board}.64bit"
+      info "If you don't need it, please run "
+      info "sudo rm -rf ${build}.64bit"
+      sudo mv ${build}{,.64bit}
+      info "Running setup_board --board=${board}"
+      ~/trunk/src/scripts/setup_board --board=${board} --skip_chroot_upgrade
+      ;;
+    esac
+  fi
+done