$ git clone -n https://src.fedoraproject.org/rpms/rust-libtest-mimic.git /var/lib/mock/f45-build-42999-799/root/chroot_tmpdir/scmroot/rust-libtest-mimic
Cloning into '/var/lib/mock/f45-build-42999-799/root/chroot_tmpdir/scmroot/rust-libtest-mimic'...
$ git fetch origin 19f9646d112b7a5257c6bb33a52832eceb078da9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-libtest-mimic
 * [new ref]         19f9646d112b7a5257c6bb33a52832eceb078da9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 19f9646 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild