perl-CPS-0.18-14.fc31 fails to build in F31 because a test fails: t/43kunfold.t ............ ok BUILDSTDERR: Can't resolve method "done_cb" overloading "&{}" in package "CPS::Future" at /usr/share/perl5/vendor_perl/Future.pm line 918. BUILDSTDERR: # Looks like your test exited with 255 before it could output anything. t/50future.t ............. Dubious, test returned 255 (wstat 65280, 0xff00) Failed 1/1 subtests A difference between passing and failing build root is at <https://apps.fedoraproject.org/koschei/build/6459116>. This is triggered by upgrading perl-Future from 0.39-2.fc30 to 0.40-1.fc31.