This exact problem is also happening on ppc64el buildd. The build log could be found at:
http://ftp.unicamp.br/pub/ppc64el/debian/buildd-upstream/build_logs/logs/libidn_1.28-2_ppc64el.build -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org