v0.7 should make the spurious failures stop (unless there is a type I didn't see), I'll keep any eye on it to be sure.
FWiW, the Can't locate WWW/Form/UrlEncoded.pm in @INC (e.g.
http://www.cpantesters.org/cpan/report/c958ec82-08fa-11e7-a3f7-2ffec63ad686)
I believe comes from a combination of installing D::P::Locale w/ ./Build and Plack::Request not having a Build.PL (it does define a prereq for WWW::Form::UrlEncoded in its Makefile.PL).
Since D::P::Locale doesn't use it directly there isn't much I can do to fix that besides tracking prereqs of prereqs … barf :/