Just ran a quick test using a PPA build of glibc with 29be63fd ("debian/patches/localedata/locale-C.diff: switch back transliterations to combining. Closes: #840199" [0] reverted and the test passes in a 17.04 (Zesty) container again.
Thanks, Nish [0] https://anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit/?id=29be63fde23ee497bb83fc9fee77171d26a7d447 -- Nishanth Aravamudan Ubuntu Server Canonical Ltd