$ git clone -n https://src.fedoraproject.org/rpms/fedora-chromium-config.git /var/lib/mock/f45-build-8844-396/root/chroot_tmpdir/scmroot/fedora-chromium-config
Cloning into '/var/lib/mock/f45-build-8844-396/root/chroot_tmpdir/scmroot/fedora-chromium-config'...
$ git fetch origin 9c306fa41c96f282973e088c03c8f3e7e847c2c8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fedora-chromium-config
 * [new ref]         9c306fa41c96f282973e088c03c8f3e7e847c2c8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9c306fa Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild