References: bsc#985503

Index: xen-4.15.1-testing/tools/hotplug/Linux/vif-route
===================================================================
--- xen-4.15.1-testing.orig/tools/hotplug/Linux/vif-route
+++ xen-4.15.1-testing/tools/hotplug/Linux/vif-route
@@ -57,11 +57,13 @@ case "${type_if}" in
 	;;
 esac
 
-# If we've been given a list of IP addresses, then add routes from dom0 to
-# the guest using those addresses.
-for addr in ${ip} ; do
-    ${cmdprefix} ip route ${ipcmd} ${addr} dev ${dev} src ${main_ip} metric ${metric}
-done
+if [ "${ip}" ] && [ "${ipcmd}" ] ; then
+    # If we've been given a list of IP addresses, then add routes from dom0 to
+    # the guest using those addresses.
+    for addr in ${ip} ; do
+        ${cmdprefix} ip route ${ipcmd} ${addr} dev ${dev} src ${main_ip} metric ${metric}
+    done
+fi
 
 handle_iptable