deploy: Add --no-merge

All of the underlying libostree APIs have supported passing `NULL`
for a merge deployment for...a long time.  But we never plumbed
it up into the CLI.

Add a `--no-merge` option to aid people who want to do a "factory reset":
https://github.com/ostreedev/ostree/issues/1793

tests/test-admin-deploy-nomerge.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+#
+# Copyright (C) 2020 Red Hat, Inc.
+#
+# SPDX-License-Identifier: LGPL-2.0+
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+set -euo pipefail
+
+. $(dirname $0)/libtest.sh
+
+# Exports OSTREE_SYSROOT so --sysroot not needed.
+setup_os_repository "archive" "syslinux"
+${CMD_PREFIX} ostree --repo=sysroot/ostree/repo pull-local --remote=testos testos-repo testos/buildmaster/x86_64-runtime
+
+echo "1..1"
+${CMD_PREFIX} ostree admin deploy --os=testos --karg=root=LABEL=foo --karg=testkarg=1 testos:testos/buildmaster/x86_64-runtime
+origdeployment=$(${CMD_PREFIX} ostree admin --sysroot=sysroot --print-current-dir)
+testconfig=etc/modified-config-file-that-will-be-removed
+touch "${origdeployment}"/"${testconfig}"
+assert_file_has_content sysroot/boot/loader/entries/ostree-1-testos.conf "^options.*root=LABEL=foo.*testkarg"
+${CMD_PREFIX} ostree admin deploy --os=testos --no-merge --karg=root=LABEL=bar testos:testos/buildmaster/x86_64-runtime
+deployment=$(${CMD_PREFIX} ostree admin --sysroot=sysroot --print-current-dir)
+assert_not_streq "${origdeployment}" "${deployment}"
+assert_not_has_file "${deployment}/${testconfig}"
+assert_file_has_content sysroot/boot/loader/entries/ostree-1-testos.conf "^options root=LABEL=bar"
+assert_not_file_has_content sysroot/boot/loader/entries/ostree-1-testos.conf "^options .*testkarg"
+echo "ok no merge deployment"