add redis-tools to dockerfile as a test-only dep

docker/Dockerfile

@@ -12,11 +12,11 @@ EXPOSE 11626
 VOLUME /data
 VOLUME /postgresql-unix-sockets
 
+ARG STELLAR_CORE_VERSION
+
 ADD setup /
 RUN /setup
 
-ARG STELLAR_CORE_VERSION
-
 #install stellar-core
 RUN wget -qO - https://apt.stellar.org/SDF.asc | apt-key add -
 RUN echo "deb https://apt.stellar.org ${DISTRO} unstable" | tee -a /etc/apt/sources.list.d/SDF-unstable.list

docker/setup

@@ -11,6 +11,11 @@ apt-get install -y wget curl python-six python3-colorama python3-pip postgresql-
 
 pip3 install awscli --upgrade  # for uploading history to s3
 
+# install test dependencies if STELLAR_CORE_VERSION ends with '~buildtests'
+if [[ "$STELLAR_CORE_VERSION" == *~buildtests ]]; then
+  apt-get install -y redis-tools
+fi
+
 # purge stuff we don't directly need
 apt-get purge -y sgml-base ucf gcc g++ xz-utils libpod-latex-perl dbus
 apt-get autoremove -y