See https://reviews.freebsd.org/D2782 for patch that updates it.
A commit references this bug: Author: kuriyama Date: Mon Jul 27 14:42:34 UTC 2015 New revision: 392982 URL: https://svnweb.freebsd.org/changeset/ports/392982 Log: - Upgrade to 1.1.0. PR: ports/200789 (https://reviews.freebsd.org/D2782) Submitted by: swills Changes: head/devel/msgpack/Makefile head/devel/msgpack/distinfo head/devel/msgpack/pkg-plist
Committed, thanks!