$ git clone -n https://src.fedoraproject.org/rpms/xapian-core.git /var/lib/mock/f45-build-38590-725/root/chroot_tmpdir/scmroot/xapian-core
Cloning into '/var/lib/mock/f45-build-38590-725/root/chroot_tmpdir/scmroot/xapian-core'...
$ git fetch origin 6502332669cb3e864436dd280b4785c8bdb0e974:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xapian-core
 * [new ref]         6502332669cb3e864436dd280b4785c8bdb0e974 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6502332 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild