$ git clone -n https://src.fedoraproject.org/rpms/ostree-pin.git /var/lib/mock/f45-build-21233-581/root/chroot_tmpdir/scmroot/ostree-pin
Cloning into '/var/lib/mock/f45-build-21233-581/root/chroot_tmpdir/scmroot/ostree-pin'...
$ git fetch origin cbce47e464b90c6ef9cda4e652e80abbeeaab443:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ostree-pin
 * [new ref]         cbce47e464b90c6ef9cda4e652e80abbeeaab443 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cbce47e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild