as with 30c6258, older [MBT] did not give other plugins a chance to add content before us

e.g.
http://www.cpantesters.org/cpan/report/63691cc8-6a67-11e4-a216-fb642fe5cfa2
Dist-Zilla-Plugin-ModuleBuildTiny-Fallback-0.013

          - avoid more test failures with older [ModuleBuildTiny]