$ git clone -n https://src.fedoraproject.org/rpms/rust-email-encoding.git /var/lib/mock/f41-build-side-1-3124876-39482/root/chroot_tmpdir/scmroot/rust-email-encoding
Cloning into '/var/lib/mock/f41-build-side-1-3124876-39482/root/chroot_tmpdir/scmroot/rust-email-encoding'...
$ git fetch origin 07caa71a28aa434d9cb7b69c7792b755dacc82b4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-email-encoding
 * [new ref]         07caa71a28aa434d9cb7b69c7792b755dacc82b4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 07caa71 unused leaf package for more than two release cycles