$ git clone -n https://src.fedoraproject.org/rpms/emacs-f.git /var/lib/mock/f45-build-8144-377/root/chroot_tmpdir/scmroot/emacs-f
Cloning into '/var/lib/mock/f45-build-8144-377/root/chroot_tmpdir/scmroot/emacs-f'...
$ git fetch origin efb7a7519e8205cd6b2cd9ebb18b2c3bf927b935:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/emacs-f
 * [new ref]         efb7a7519e8205cd6b2cd9ebb18b2c3bf927b935 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at efb7a75 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild