$ git clone -n https://src.fedoraproject.org/rpms/R-bookdown.git /var/lib/mock/f38-build-side-42-init-devel-860350-28427/root/chroot_tmpdir/scmroot/R-bookdown
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-860350-28427/root/chroot_tmpdir/scmroot/R-bookdown'...
$ git fetch origin ac1f9e3ec746acbc72e4d11ad128f6489b9d0b8e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-bookdown
 * [new ref]         ac1f9e3ec746acbc72e4d11ad128f6489b9d0b8e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ac1f9e3 0.33