$ git clone -n https://src.fedoraproject.org/rpms/rust-regex-test.git /var/lib/mock/f45-build-44390-813/root/chroot_tmpdir/scmroot/rust-regex-test
Cloning into '/var/lib/mock/f45-build-44390-813/root/chroot_tmpdir/scmroot/rust-regex-test'...
$ git fetch origin b6418db46f299ac9bb51303774b12c21ae5c27c7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-regex-test
 * [new ref]         b6418db46f299ac9bb51303774b12c21ae5c27c7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6418db Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild