$ git clone -n https://src.fedoraproject.org/rpms/R-stringr.git /var/lib/mock/f40-build-2033316-47790/root/chroot_tmpdir/scmroot/R-stringr
Cloning into '/var/lib/mock/f40-build-2033316-47790/root/chroot_tmpdir/scmroot/R-stringr'...
$ git fetch origin 5489afb505af7b46ffbbc6fccc008bb4540e2bdf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-stringr
 * [new ref]         5489afb505af7b46ffbbc6fccc008bb4540e2bdf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5489afb 1.5.1