$ git clone -n https://src.fedoraproject.org/rpms/rust-png.git /var/lib/mock/f40-build-2251020-54102/root/chroot_tmpdir/scmroot/rust-png
Cloning into '/var/lib/mock/f40-build-2251020-54102/root/chroot_tmpdir/scmroot/rust-png'...
$ git fetch origin d3a078ed427ce277afbc69ae1c3fc799e3ce0a10:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-png
 * [new ref]         d3a078ed427ce277afbc69ae1c3fc799e3ce0a10 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d3a078e Update to version 0.17.11; Fixes RHBZ#2258269