libs/sys: workaround broken entries in /proc/net/ipv6_route, observed on brcm-2.4

libs/sys/luasrc/sys.lua

@@ -451,6 +451,12 @@ function net.routes6(callback)
 				"([a-f0-9]+) +([^%s]+)"
 			)
 
+			if dst_ip and dst_prefix and
+			   src_ip and src_prefix and
+			   nexthop and metric and
+			   refcnt and usecnt and
+			   flags and dev
+			then
 				src_ip = luci.ip.Hex(
 					src_ip, tonumber(src_prefix, 16), luci.ip.FAMILY_INET6, false
 				)
@@ -482,6 +488,7 @@ function net.routes6(callback)
 					routes[#routes+1] = rt
 				end
 			end
+		end
 
 		return routes
 	end