Fix install command for nodejs

Author: betatim

repo2docker/buildpacks/base.py

@@ -43,10 +43,10 @@
     ${NB_USER}
 WORKDIR ${HOME}
 
-RUN wget --quiet -O - https://deb.nodesource.com/gpgkey/nodesource.gpg.key |  apt-key add - \
-    DISTRO="$(lsb_release -s -c)" \
-    echo "deb https://deb.nodesource.com/node_10.x $DISTRO main" |  tee /etc/apt/sources.list.d/nodesource.list \
-    echo "deb-src https://deb.nodesource.com/node_10.x $DISTRO main" |  tee -a /etc/apt/sources.list.d/nodesource.list
+RUN wget --quiet -O - https://deb.nodesource.com/gpgkey/nodesource.gpg.key |  apt-key add - && \
+    DISTRO="$(lsb_release -s -c)" && \
+    echo "deb https://deb.nodesource.com/node_10.x $DISTRO main" >> /etc/apt/sources.list.d/nodesource.list && \
+    echo "deb-src https://deb.nodesource.com/node_10.x $DISTRO main" >> /etc/apt/sources.list.d/nodesource.list
 
 RUN apt-get update && \
     apt-get install --yes --no-install-recommends \