$ git clone -n https://src.fedoraproject.org/rpms/rust-serde-json-core.git /var/lib/mock/f45-build-44837-818/root/chroot_tmpdir/scmroot/rust-serde-json-core
Cloning into '/var/lib/mock/f45-build-44837-818/root/chroot_tmpdir/scmroot/rust-serde-json-core'...
$ git fetch origin 891e5742f9542c13303daddb3565f6ff155fd121:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde-json-core
 * [new ref]         891e5742f9542c13303daddb3565f6ff155fd121 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 891e574 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild