Actually, when I looked more closely - the machine I was running the
  server on was using lwp-1.xx, nearly neolithic.  It looks like the
  version checks for pkgsrc are a bit too lenient.

The lwp buildlink file says:

BUILDLINK_API_DEPENDS.lwp+=     lwp>=1.6
BUILDLINK_ABI_DEPENDS.lwp+=     lwp>=1.10nb1

I am not quite clear on the right thing here; should I bet setting both
of those to 2.3, or should the coda package force 2.3?

What version does coda need?

Have there been ABI changes since 1.10?