The issue was fixed through https://git.savannah.gnu.org/gitweb/?p=gettext.git;a=commitdiff;h=b67399b40bc5bf3165b09e6a095ec941d4b30a97 and is thus contained in gettext-0.19.8 and newer.
The *gettext functions in musl libc work seamlessly with .mo files produced by msgfmt 0.22 or newer, except for the 'I' flag in format strings, that musl libc does not support. Bruno
