Make use of the new --puppet-classes option.

Author: alexmv

Dockerfile

@@ -67,8 +67,8 @@ RUN \
     mv zulip-server-docker zulip && \
     cp -rf /root/custom_zulip/* /root/zulip && \
     rm -rf /root/custom_zulip && \
-    export PUPPET_CLASSES="zulip::profile::docker" && \
-    /root/zulip/scripts/setup/install --hostname="$(hostname)" --email="docker-zulip" --no-init-db && \
+    /root/zulip/scripts/setup/install --hostname="$(hostname)" --email="docker-zulip" \
+      --puppet-classes="zulip::profile::docker" && \
     rm -f /etc/zulip/zulip-secrets.conf /etc/zulip/settings.py && \
     apt-get -qq autoremove --purge -y && \
     apt-get -qq clean && \