message: during testing, sometimes the datadir/data could not be removed; rename it instead so the conversion does not happen again.
diff: @@ -15,7 +15,7 @@ if [ -n "$(ls /var/solr)" ]; then
  # the datadir now has the layout that a newly created core would.
  mv ${datadir}/data/* ${datadir}/
  # remove empty directory
  - rm -Rf ${datadir}/data
  + rm -Rf ${datadir}/data || mv ${datadir}/data ${datadir}/data-delete
  fi
  # the new place for config is in the container, in /opt/solr/server/solr/${corename}
  