$ git clone -n https://src.fedoraproject.org/rpms/rust-postcard.git /var/lib/mock/f45-build-43940-809/root/chroot_tmpdir/scmroot/rust-postcard
Cloning into '/var/lib/mock/f45-build-43940-809/root/chroot_tmpdir/scmroot/rust-postcard'...
$ git fetch origin f4dd9d161c1031350fc42f2d054bc780b140bdc8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-postcard
 * [new ref]         f4dd9d161c1031350fc42f2d054bc780b140bdc8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4dd9d1 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild