cros_workon: check for existence of local manifest before cat

cros_workon

 #!/bin/bash
 
 # Copyright (c) 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.
 
 # This script moves ebuilds between 'stable' and 'live' states.
 # By default 'stable' ebuilds point at and build from source at the
 # last known good commit. Moving an ebuild to 'live' (via cros_workon start)
 # is intended to support development. The current source tip is fetched,
@@ skipping 114 matching lines @@
   exit 1
 }
 
 
 # This is called only for "cros-workon start". We dont handle the "stop" case since the local changes are ignored anyway since the 9999.ebuild is masked and we dont want to deal with what to do with the user's local changes.
 regen_manifest_and_sync() {
   find_repo_dir
   local_manifest="${REPODIR}/local_manifest.xml"
 
   # preserve old manifest entries
-  MANIFEST_ENTRIES_OLD=$(cat "${local_manifest}" | grep "^<project")
+  [ -f "${local_manifest}" ] && \
+    MANIFEST_ENTRIES_OLD=$(cat "${local_manifest}" | grep "^<project")
 
   rm -f "${local_manifest}"
 
   # get new manifest entries
   MANIFEST_ENTRIES=$(cat ${KEYWORDS_FILE} |
   {
     while read line
     do
       pkgname=`basename ${line}`
       eval $(${EBUILDCMD} $(${EQUERYCMD} which ${pkgname}) info)
@@ skipping 80 matching lines @@
   esac
 fi
 
 case ${WORKON_CMD} in
   start)  ebuild_to_live "${ATOM_LIST}"; regen_manifest_and_sync ;;
   stop)   ebuild_to_stable "${ATOM_LIST}" ;;
   list)   [ ${FLAGS_all} = "${FLAGS_FALSE}" ] && show_live_ebuilds || show_workon_ebuilds ;;
   iterate)ebuild_iterate "${ATOM_LIST}" ;;
   *)      die "invalid cros_workon command" ;;
 esac