--- isc-dhcp-4.3.5/debian/dhclient-script.linux	2017-01-19 09:11:21.000000000 -0800
+++ /sbin/dhclient-script	2017-09-20 21:03:43.684655125 -0700
@@ -170,6 +170,9 @@
                 error "$dev: ipv6 dad failed."
                 return 1;;
             *\ tentative\ *) :;;
+            "  ")
+                :
+                ;;
             *) return 0;;
         esac
         [ $n -lt $attempts ] || {