$ git clone -n https://src.fedoraproject.org/rpms/rubygem-slim.git /var/lib/mock/f45-build-35318-694/root/chroot_tmpdir/scmroot/rubygem-slim
Cloning into '/var/lib/mock/f45-build-35318-694/root/chroot_tmpdir/scmroot/rubygem-slim'...
$ git fetch origin daf23390bfcd8d51cb78eb5197c6105185c2356b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-slim
 * [new ref]         daf23390bfcd8d51cb78eb5197c6105185c2356b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at daf2339 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild