$ git clone -n https://src.fedoraproject.org/rpms/rust-block-buffer0.10.git /var/lib/mock/f45-build-40491-772/root/chroot_tmpdir/scmroot/rust-block-buffer0.10
Cloning into '/var/lib/mock/f45-build-40491-772/root/chroot_tmpdir/scmroot/rust-block-buffer0.10'...
$ git fetch origin aa1367c8b20b6fcabdb1cf699bc1be1dd2add6f6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-block-buffer0.10
 * [new ref]         aa1367c8b20b6fcabdb1cf699bc1be1dd2add6f6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at aa1367c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild