$ git clone -n https://src.fedoraproject.org/rpms/rust-unicode-xid0.1.git /var/lib/mock/f42-build-3251789-41222/root/chroot_tmpdir/scmroot/rust-unicode-xid0.1
Cloning into '/var/lib/mock/f42-build-3251789-41222/root/chroot_tmpdir/scmroot/rust-unicode-xid0.1'...
$ git fetch origin c1fcf210239c68db59412c784aaed50657c848c0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-unicode-xid0.1
 * [new ref]         c1fcf210239c68db59412c784aaed50657c848c0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c1fcf21 compat package no longer needed