Updating hammer script based on review suggestions.

hammer

 #!/bin/sh
 #
 # Copyright (c) 2006-2008 The Chromium 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 script to invoke scons in gyp generated projects.
 
 # Find the 'src' directory by looking for the site_scons directory.
 # This method allows trees that don't use the name src to use this script.
 # Explicitly skip site_scons directories that are from the 'software
 # construction toolkit', since these are not gyp compatible.
 SRC_DIR=`pwd`
-while `test ! -d "${SRC_DIR}/site_scons" -o \
-       -e "${SRC_DIR}/site_scons/site_tools/component_setup.py"`; do
-  PARENT_DIR="$(dirname ${SRC_DIR})"
-  if `test "${SRC_DIR}" = "${PARENT_DIR}"`; then
+while [ ! -d "${SRC_DIR}/site_scons" ] || \
+      [ -e "${SRC_DIR}/site_scons/site_tools/component_setup.py" ]; do
+  PARENT_DIR="$(dirname "${SRC_DIR}")"
+  if [ "${SRC_DIR}" = "${PARENT_DIR}" ]; then
     echo "ERROR: hammer must be run in a directory with site_scons under" >&2
     echo "       the root of the project tree." >&2
     exit 1
   fi
   SRC_DIR="${PARENT_DIR}"
 done
 
 SCONS="${SRC_DIR}/third_party/scons/scons.py"
 SITE_SCONS="${SRC_DIR}/site_scons"
 
 exec python "${SCONS}" "--site-dir=${SITE_SCONS}" "$@"