$ git clone -n https://src.fedoraproject.org/rpms/rust-bytecount.git /var/lib/mock/f39-build-1466661-33688/root/chroot_tmpdir/scmroot/rust-bytecount
Cloning into '/var/lib/mock/f39-build-1466661-33688/root/chroot_tmpdir/scmroot/rust-bytecount'...
$ git fetch origin b8fa717c891808939f170068f0f1a262b78a2450:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-bytecount
 * [new ref]         b8fa717c891808939f170068f0f1a262b78a2450 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b8fa717 Update to version 0.6.4; Fixes RHBZ#2241659