$ git clone -n https://src.fedoraproject.org/rpms/rust-png.git /var/lib/mock/f40-build-2083233-49900/root/chroot_tmpdir/scmroot/rust-png
Cloning into '/var/lib/mock/f40-build-2083233-49900/root/chroot_tmpdir/scmroot/rust-png'...
$ git fetch origin d5bacf438f473603389ac2abf6a7f7d81d51bfc0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-png
 * [new ref]         d5bacf438f473603389ac2abf6a7f7d81d51bfc0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d5bacf4 Update to version 0.17.10; Fixes RHBZ#2232717