Fix broken docker build due to pip-19.0

pip-19.0 fails to build with the option --no-cache-dir

Change-Id: I6494c6c6b4dc49d4fbd2ce657ed9824c5b3847e3
Issue-ID: OOM-1607
Signed-off-by: Petr Ospalý <p.ospaly@partner.samsung.com>
diff --git a/ansible/docker/Dockerfile b/ansible/docker/Dockerfile
index 4cefa8b..f249d3b 100644
--- a/ansible/docker/Dockerfile
+++ b/ansible/docker/Dockerfile
@@ -20,12 +20,12 @@
   py3-openssl \
   openssh \
   sshpass \
-&& pip3 install --no-cache-dir --upgrade pip \
-&& pip3 install --no-cache-dir \
+&& pip3 install --upgrade pip \
+&& pip3 install \
   ansible==$ansible_version \
   jmespath \
   netaddr \
-&& apk del build-dependencies && rm -rf /var/cache/apk/*
+&& apk del build-dependencies && rm -rf /var/cache/apk/* && rm -rf /root/.cache
 
 ENV ANSIBLE_HOST_KEY_CHECKING false
 ENV ANSIBLE_RETRY_FILES_ENABLED false