$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rest-client.git /var/lib/mock/f39-build-1499447-34744/root/chroot_tmpdir/scmroot/rubygem-rest-client
Cloning into '/var/lib/mock/f39-build-1499447-34744/root/chroot_tmpdir/scmroot/rubygem-rest-client'...
$ git fetch origin 8683fec6c1f64f87b81422daf1b3f3d07bceae3a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rest-client
 * [new ref]         8683fec6c1f64f87b81422daf1b3f3d07bceae3a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8683fec Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild