$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_default.git /var/lib/mock/f45-build-44867-818/root/chroot_tmpdir/scmroot/rust-serde_default
Cloning into '/var/lib/mock/f45-build-44867-818/root/chroot_tmpdir/scmroot/rust-serde_default'...
$ git fetch origin f5f600a09cd9167fbdb1d1ddc416cd228aceaccc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_default
 * [new ref]         f5f600a09cd9167fbdb1d1ddc416cd228aceaccc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f5f600a Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild