Fix reporting of shard number in buildbot

build_tools/buildbot_build_shard.sh

 #!/bin/bash
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 ######################################################################
 # Notes on directory layout:
 # makefile location (base_dir):  naclports/src
 # toolchain injection point:     specified externally via NACL_SDK_ROOT.
 ######################################################################
 
 SCRIPT_DIR="$(cd $(dirname $0) && pwd)"
 source ${SCRIPT_DIR}/buildbot_common.sh
 
 set -o nounset
 set -o errexit
 
 readonly PARTCMD="${PYTHON} build_tools/partition.py"
 readonly SHARD_CMD="${PARTCMD} -t ${SHARD} -n ${SHARDS}"
-echo "Calculating targets for shard ${SHARD} of ${SHARDS}"
+echo "Calculating targets for shard $((${SHARD} + 1)) of ${SHARDS}"
 readonly PACKAGE_LIST=$(${SHARD_CMD})
 if [ -z "${PACKAGE_LIST}" ]; then
   echo "sharding command failed: ${SHARD_CMD}"
   exit 1
 fi
 
 echo "Building the following packages: ${PACKAGE_LIST}"
 for PKG in ${PACKAGE_LIST}; do
   InstallPackageMultiArch ${PKG}
 done
 
 echo "@@@BUILD_STEP Summary@@@"
 if [[ ${RESULT} != 0 ]] ; then
   echo "@@@STEP_FAILURE@@@"
   echo -e "${MESSAGES}"
 fi
 
 exit ${RESULT}