$ git clone -n https://src.fedoraproject.org/rpms/perl-POSIX-2008.git /var/lib/mock/f41-build-815958-149914/root/chroot_tmpdir/scmroot/perl-POSIX-2008
Cloning into '/var/lib/mock/f41-build-815958-149914/root/chroot_tmpdir/scmroot/perl-POSIX-2008'...
$ git fetch origin e82e4a1fed9a9a7ffae31edbf5492fcb7099eab8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-POSIX-2008
 * [new ref]         e82e4a1fed9a9a7ffae31edbf5492fcb7099eab8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e82e4a1 Perl 5.40 rebuild