$ git clone -n https://src.fedoraproject.org/rpms/libfixposix.git /var/lib/mock/f45-build-16166-483/root/chroot_tmpdir/scmroot/libfixposix
Cloning into '/var/lib/mock/f45-build-16166-483/root/chroot_tmpdir/scmroot/libfixposix'...
$ git fetch origin bc7bb76560de0e392c93a1d5a0002419055be8e3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libfixposix
 * [new ref]         bc7bb76560de0e392c93a1d5a0002419055be8e3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bc7bb76 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild