Stop the daemon in the preinst script when renaming the .service file

Stop the daemon in the preinst script instead of the postinst one when
renaming the .service file as it now contains the "Restart=on-failure"
option and blindly killing the daemon is not working anymore.

This completes the fix for #730604

debian/libvirt-daemon-system.postinst

@@ -96,18 +96,6 @@ case "$1" in
         add_users_groups
         add_statoverrides
 
-	# When renaming the .service file, systemd might become confused, we
-	# need to ensure that the libvirtd daemon is fully stopped before
-	# trying to restart it again. (Bug: #730604)
-	if dpkg --compare-versions "$2" le "1.2.6-1~"; then
-	    if [ -d /run/systemd/system ]; then
-	        start-stop-daemon --stop --quiet --pidfile /var/run/libvirtd.pid \
-		    --oknodo --exec /usr/sbin/libvirtd --retry 1
-	    fi
-	    # Remove everything we know about libvirt-bin.service
-	    deb-systemd-helper purge libvirt-bin.service >/dev/null
-	fi
-
 	# Make sure the directories don't get removed on package removal since
 	# logrotate chokes otherwise.
 	for dir in qemu uml lxc; do

debian/libvirt-daemon-system.preinst

+#!/bin/sh
+# preinst script for libvirt-daemon-system
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# summary of how this script can be called:
+#        * <new-preinst> `install'
+#        * <new-preinst> `install' <old-version>
+#        * <new-preinst> `upgrade' <old-version>
+#        * <old-preinst> `abort-upgrade' <new-version>
+# for details, see http://www.debian.org/doc/debian-policy/ or
+# the debian-policy package
+
+
+case "$1" in
+    install|upgrade)
+	# When renaming the .service file, systemd might become confused, we
+	# need to ensure that the libvirtd daemon is fully stopped before
+	# trying to restart it again. (Bug: #730604)
+	if dpkg --compare-versions "$2" le-nl "1.2.6-1~"; then
+	    if [ -d /run/systemd/system ]; then
+	        invoke-rc.d libvirt-bin stop
+	    fi
+	    # Remove everything we know about libvirt-bin.service
+	    deb-systemd-helper purge libvirt-bin.service >/dev/null
+	    deb-systemd-helper unmask libvirt-bin.service >/dev/null
+	fi
+    ;;
+
+    abort-upgrade)
+    ;;
+
+    *)
+        echo "preinst called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0