Jeffrey Kegler sent me this link to an UNKNOWN report I sent:
http://www.cpantesters.org/cpan/report/0bc3d00a-b477-11e2-8256-6174c1508286
From the report I cannot tell what happened before the cpan shell called 'make'. But since there seems to be no Makefile, it would be really interesting to see the output of the makefile_pl phase (especially because in this case I cannot reproduce what happened there).
https://rt.cpan.org/Ticket/Display.html?id=85055