[CentOS] C7, NetworkMangler, and IPv6

Hi, folks,

   Freshly built box... but does not get its IPv6 address. Gets its IPv4
with no trouble, and if I *manually* run dhclient -v -N eno1, it gets
the correct IPv6, but after that, nope. And INITIPV^=yes in
/etc/sysconfig/network-scripts/ifcfg-eno1. I even tried adding
NETWORKING_IPV6=yes to an otherwise empty /etc/sysconfig/network.

   What am I missing?

         mark