$ git clone -n https://src.fedoraproject.org/rpms/perl.git /var/lib/mock/f40-build-775823-128455/root/chroot_tmpdir/scmroot/perl
Cloning into '/var/lib/mock/f40-build-775823-128455/root/chroot_tmpdir/scmroot/perl'...
$ git fetch origin 172ca0a5c1f3c32cb07d897f2b6c98e51950a76c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl
 * [new ref]         172ca0a5c1f3c32cb07d897f2b6c98e51950a76c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 172ca0a Update Compress::Raw::Zlib for improved compatibility with zlib-ng