When used with [Git::CommitBuild] only jobs using Perl versions provided by default work

[pwr22]

This seems to be because the .travis.yml committed to the build branch lacks any of the Perl helper stuff

[pwr22]

line 294 in lib/Dist/Zilla/Role/TravisYML.pm also appears to be broken too, which means that the helper stuff will also be omitted if support_builddir == 0

[pwr22]

I've confirmed the above issue occurs in the .travis.yml generated

[pwr22]

The issue was introduced in PR #23, behaviour was correct before