$ git clone -n https://src.fedoraproject.org/rpms/rust-uuid0.7.git /var/lib/mock/f42-build-3251832-41222/root/chroot_tmpdir/scmroot/rust-uuid0.7
Cloning into '/var/lib/mock/f42-build-3251832-41222/root/chroot_tmpdir/scmroot/rust-uuid0.7'...
$ git fetch origin acf1beebd18f875d1b5a1b22f21da98aed37b9a0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uuid0.7
 * [new ref]         acf1beebd18f875d1b5a1b22f21da98aed37b9a0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at acf1bee compat package no longer needed