maybe =/== is not compatible issue between bin/bash bin/sh.

28-Feb-2018 15:48:39 Step 1/1 : ADD . /home/clowder/
28-Feb-2018 15:48:39 Step 1/1 : RUN if [ -e packages.apt ]; then                 apt-get -q -q update                 && xargs apt-get -y install --no-install-recommends < packages.apt                 && rm -rf /var/lib/apt/lists/*;             fi
28-Feb-2018 15:48:39 ---> Running in f47c5b54202f
28-Feb-2018 15:48:41 Step 1/1 : RUN if [ -e requirements.txt ]; then                 pip install --no-cache-dir -r requirements.txt;             fi
28-Feb-2018 15:48:41 ---> Running in b3fec2fbc001
28-Feb-2018 15:48:42 Step 1/1 : USER clowder
28-Feb-2018 15:48:42 ---> Running in a2ee34624dda
28-Feb-2018 15:48:42 ---> a0cfaf6662e4
28-Feb-2018 15:48:42 Removing intermediate container 0f069f41cf53
28-Feb-2018 15:48:42 Removing intermediate container f47c5b54202f
28-Feb-2018 15:48:42 Removing intermediate container b3fec2fbc001
28-Feb-2018 15:48:42 Removing intermediate container a2ee34624dda
28-Feb-2018 15:48:42 Step 2/2 : ENV RABBITMQ_QUEUE "ncsa.wordcount" MAIN_SCRIPT "wordcount.py"
28-Feb-2018 15:48:42 ---> Running in db87f9db6d79
28-Feb-2018 15:48:43 ---> 5d1ef22e0fad
28-Feb-2018 15:48:43 Removing intermediate container db87f9db6d79
28-Feb-2018 15:48:43 Successfully built 5d1ef22e0fad
28-Feb-2018 15:48:43 docker.sh: 13: [: master: unexpected operator