Intermittent test failures with various perl versions

[cpansprout]

See https://rt.cpan.org/Ticket/Display.html?id=88823, https://rt.cpan.org/Ticket/Display.html?id=76404, and https://rt.perl.org/rt3/Ticket/Display.html?id=119771.

Data::MessagePack does not guarantee that it will sort hash keys, but because it reads uninitialized memory when deciding whether to do it, sometimes it will, and sometimes it won’t. This causes test failures for Data::Model, which expects canonical order without asking for it. The patch attached to https://rt.cpan.org/Ticket/Display.html?id=76404 fixes the problem.

Apologies for doing it this way, but GitHub does not make it easy to attach patches. Usually when I am trying to figure out why modules are failing with new perl versions I already have a patch made before I even find out where the bug tracker is.