$ git clone -n https://src.fedoraproject.org/rpms/fex.git /var/lib/mock/f45-build-8930-397/root/chroot_tmpdir/scmroot/fex
Cloning into '/var/lib/mock/f45-build-8930-397/root/chroot_tmpdir/scmroot/fex'...
$ git fetch origin 86574adedaac81ba3aaa9946ac1b46232a88b2c7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fex
 * [new ref]         86574adedaac81ba3aaa9946ac1b46232a88b2c7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 86574ad Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild