OS-4158 zombie vnics lurking in the system

Reviewed by: Rob Gulewich <robert.gulewich@joyent.com>

overlay/generic/usr/lib/brand/jcommon/statechange

@@ -262,12 +262,23 @@ setup_net()
 		# Create the vnic.
 		#
 
-		opt_str="-p zone=$ZONENAME"
+		opt_str="-p "
 
 		if [[ -n "$mtu" ]]; then
-			opt_str="$opt_str,mtu=$mtu"
+			opt_str="$opt_str mtu=$mtu,"
 		fi
 
+		#
+		# Always append the zone as the last property. This is
+		# to work around the fact that once we associate it with
+		# a zone, the zone will have a hold on the device and
+		# we'll not be able to delete it if a create fails due
+		# to a bad property (say an invalid MTU). Note if we
+		# have other properties, it is their responsibility to
+		# put a trailing comma on it.
+		#
+		opt_str="${opt_str}zone=$ZONENAME"
+
 		if [[ -n "$jst_vrrp" && -n $vrid ]]; then
 			# MAC addresses for VRRP vnics are determined by the VRID
 			mac_addr="vrrp"
@@ -279,6 +290,7 @@ setup_net()
 		[[ -n $vlan_id && $vlan_id != 0 ]] && \
 		    opt_str="$opt_str -v $vlan_id"
 
+
 		#
 		# Creating a VNIC in a zone is a multi-step process internally.
 		# This means there is a short window where the VNIC exists in