$ git clone -n https://src.fedoraproject.org/rpms/perl-Class-C3-XS.git /var/lib/mock/f45-build-22316-590/root/chroot_tmpdir/scmroot/perl-Class-C3-XS
Cloning into '/var/lib/mock/f45-build-22316-590/root/chroot_tmpdir/scmroot/perl-Class-C3-XS'...
$ git fetch origin 77879a5ec887b187983180e81fefd12d2dabe0a0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Class-C3-XS
 * [new ref]         77879a5ec887b187983180e81fefd12d2dabe0a0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 77879a5 Perl 5.44 rebuild