$ git clone -n https://src.fedoraproject.org/rpms/perl-Image-PNG-Libpng.git /var/lib/mock/f45-build-24245-602/root/chroot_tmpdir/scmroot/perl-Image-PNG-Libpng
Cloning into '/var/lib/mock/f45-build-24245-602/root/chroot_tmpdir/scmroot/perl-Image-PNG-Libpng'...
$ git fetch origin b2921f61a070808cabf8b32f1336198dda386e93:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Image-PNG-Libpng
 * [new ref]         b2921f61a070808cabf8b32f1336198dda386e93 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b2921f6 Perl 5.44 rebuild