try to fix missing root dir

docker/Dockerfile.do.linux.amd64

@@ -31,10 +31,9 @@ RUN \
     apk update \
     && apk add --update --no-cache ${PACKAGES} \
     && rm -rf /var/cache/apk/* \
-    && pip install --upgrade pip \
+    && pip install --upgrade --no-cache-dir pip \
     && pip install --no-cache-dir ${PIP_PACKAGES} \
-    && rm -rf /root/.cache \
-    && mkdir /root
+    && rm -rf /root/.cache/
 
 USER root
 ENTRYPOINT ["/docker-entrypoint.sh"]

docker/Dockerfile.ec2.linux.amd64

@@ -32,10 +32,9 @@ RUN \
     apk update \
     && apk add --update --no-cache ${PACKAGES} \
     && rm -rf /var/cache/apk/* \
-    && pip install --upgrade pip \
+    && pip install --upgrade --no-cache-dir pip \
     && pip install --no-cache-dir ${PIP_PACKAGES} \
-    && rm -rf /root/.cache \
-    && mkdir /root
+    && rm -rf /root/.cache/
 
 USER root
 ENTRYPOINT ["/docker-entrypoint.sh"]

docker/Dockerfile.gce.linux.amd64

@@ -32,10 +32,10 @@ RUN \
     apk update \
     && apk add --update --no-cache ${PACKAGES} \
     && rm -rf /var/cache/apk/* \
-    && pip install --upgrade pip \
+    && pip install --upgrade --no-cache-dir pip \
     && pip install --no-cache-dir ${PIP_PACKAGES} \
-    && rm -rf /root/.cache \
-    && mkdir -p /root/.ssh \
+    && rm -rf /root/.cache/ \
+    && mkdir /root/.ssh \
     && chmod 700 /root/.ssh
 
 USER root

docker/Dockerfile.hcloud.linux.amd64

@@ -21,7 +21,6 @@ ENV PACKAGES="\
 ENV PIP_PACKAGES="\
     ansible~=2.8.0 \
     molecule[hetznercloud] \
-    virtualenv \
     pycrypto \
     hcloud \
 "
@@ -32,10 +31,9 @@ RUN \
     apk update \
     && apk add --update --no-cache ${PACKAGES} \
     && rm -rf /var/cache/apk/* \
-    && pip install --upgrade pip \
+    && pip install --upgrade --no-cache-dir pip \
     && pip install --no-cache-dir ${PIP_PACKAGES} \
-    && rm -rf /root/.cache \
-    && mkdir /root
+    && rm -rf /root/.cache/
 
 USER root
 ENTRYPOINT ["/docker-entrypoint.sh"]