remove useless local variable
make this changelog entry more accurate
allow tests to pass with Dist::Zilla::Role::TestRunner < 5.014

e.g.
http://www.cpantesters.org/cpan/report/739bd477-6c15-1014-8865-4c0123feeb79
Dist-Zilla-Plugin-ModuleBuildTiny-Fallback-0.008

          - fix test failure caused by unstated assumption that
            Dist::Zilla::Role::TestRunner is a very recent version