Perl 5.30.0 (edge) has a group ID setting bug that breaks h2o's fastcgi

Perl 5.30.0 has a bug which causes code that sets supplementary group IDs to break. The h2o web server uses a perl script (/usr/share/h2o/setuidgid) to drop privileges when running fastcgi using fastcgi.spawn.

The best solution would be to backport the fix to the perl bug, but alternatively one could delay Perl 5.30 landing to the stable until upstream resolves the issue.