$ git clone -n https://src.fedoraproject.org/rpms/python-b4.git /var/lib/mock/f45-build-29715-640/root/chroot_tmpdir/scmroot/python-b4
Cloning into '/var/lib/mock/f45-build-29715-640/root/chroot_tmpdir/scmroot/python-b4'...
$ git fetch origin 6bdc0b110460c762d57d98790a343c0204bb87f2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-b4
 * [new ref]         6bdc0b110460c762d57d98790a343c0204bb87f2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6bdc0b1 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild