The NetBSD-current/i386 build is working again. The following commits were made between the last failed build and the successful build:
2017.04.04.16.49.15 sevan src/sys/net/if_l2tp.c,v 1.7 2017.04.04.16.49.15 sevan src/sys/netinet6/in6_l2tp.c,v 1.4 Log files can be found at: http://releng.NetBSD.org/b5reports/i386/commits-2017.04.html#2017.04.04.16.49.15