$ git clone -n https://src.fedoraproject.org/rpms/rust-platforms.git /var/lib/mock/f45-build-43938-809/root/chroot_tmpdir/scmroot/rust-platforms
Cloning into '/var/lib/mock/f45-build-43938-809/root/chroot_tmpdir/scmroot/rust-platforms'...
$ git fetch origin 21047cfac3853aab77310525fcf88e8e31bdd15f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-platforms
 * [new ref]         21047cfac3853aab77310525fcf88e8e31bdd15f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 21047cf Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild