pam_google is no longer in the image, so we must create /etc/login_trust_root.pem from scratch

mod_for_test_scripts/710enableAuthTesting

 #!/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.
 
 echo "Adding mock Google Accounts server certs."
 
 case "${ARCH}" in
   arm*)
@@ skipping 26 matching lines @@
 sudo chroot "${ROOT_FS_DIR}" ${QEMU} \
   /usr/local/bin/nsscertutil -d sql:"${FAKE_NSSDB}" -N -f <(echo "")
 cp "${ROOT_FS_DIR}/${TMP_KEY}" "${ROOT_FS_DIR}/${FAKE_CA_DIR}/${CERT_NAME}.key"
 cp "${ROOT_FS_DIR}/${TMP_CERT}" "${ROOT_FS_DIR}/${FAKE_CA_DIR}/${CERT_NAME}.pem"
 echo "DO NOT MOVE THIS DATA OFF OF THE ROOTFS!" > "${ROOT_FS_DIR}/${FAKE_CA_DIR}/README"
 sudo chroot "${ROOT_FS_DIR}" ${QEMU} \
   /usr/local/bin/nsscertutil -d sql:"${FAKE_NSSDB}" -A \
   -n FakeCert -t "C,," -a -i "${FAKE_CA_DIR}/${CERT_NAME}.pem"
 chmod 0644 "${ROOT_FS_DIR}/${FAKE_NSSDB}"/*
 
-# TODO(cmasone): get rid of this once we're off pam_google for good.
-# Sadly, our fake cert HAS to be first in this file.
-TMPFILE=$(mktemp)
 CERT_FILE="${ROOT_FS_DIR}/etc/login_trust_root.pem"
-PERMS=$(stat --printf="%a" "${CERT_FILE}")
-cat "${ROOT_FS_DIR}/${TMP_CERT}" "${CERT_FILE}" > "${TMPFILE}"
-mv -f "${TMPFILE}" "${CERT_FILE}"
-chmod "${PERMS}" "${CERT_FILE}"
+mv -f "${ROOT_FS_DIR}/${TMP_CERT}" "${CERT_FILE}"
+chmod 0644 "${CERT_FILE}"
 
 if [ -n "${QEMU}" ] ; then
     rm "${ROOT_FS_DIR}/${QEMU}"
 fi
-rm "${ROOT_FS_DIR}/${TMP_KEY}"
-rm "${ROOT_FS_DIR}/${TMP_CERT}"
+rm -f "${ROOT_FS_DIR}/${TMP_KEY}"
+rm -f "${ROOT_FS_DIR}/${TMP_CERT}"