$ git clone -n https://src.fedoraproject.org/rpms/rubygem-childprocess.git /var/lib/mock/f39-build-1686913-41102/root/chroot_tmpdir/scmroot/rubygem-childprocess
Cloning into '/var/lib/mock/f39-build-1686913-41102/root/chroot_tmpdir/scmroot/rubygem-childprocess'...
$ git fetch origin 19e16da4314f06781113fd270e32edbf67225ee2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-childprocess
 * [new ref]         19e16da4314f06781113fd270e32edbf67225ee2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 19e16da Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild