dtrace failing with "no struct pkt_node definition is available"

[Ryan Stone]

I'm getting this error when I try to run dtrace on a recent head:

dtrace: failed to compile script error.d: "/usr/lib/dtrace/tcp.d", line
292: operator -> cannot be applied to a forward declaration: no struct
pkt_node definition is available.

I confirmed that I do have ctf data in my kernel.  I was able to get the
dtrace script to run by removing tcp.d.  Has something changed in the
kernel that tcp.d needs to catch up with?