message: run nbextension enable, do not exec
diff: @@ -37,7 +37,7 @@ cp {{MLDB_PUBLIC_HTML_PATH}}/resources/images/mldb_ipython_logo.png {{IPYTHON_IM
  export JUPYTER_CONFIG_DIR={{IPYTHON_DIR}}/config
  export SHELL="/bin/bash"
  -exec /sbin/setuser _mldb \
  +/sbin/setuser _mldb \
  /usr/local/bin/jupyter nbextension enable --py --sys-prefix widgetsnbextension
  exec /sbin/setuser _mldb \
  