New set of fixes

build-executor/Dockerfile

@@ -21,6 +21,18 @@ RUN yum install -y docker-ce \
     http://ecsft.cern.ch/dist/cvmfs/nightlies/cvmfs-git-886/cvmfs-2.6.0-0.886.21671f0a65e19b91git.el7.x86_64.rpm \
     && yum clean all
 
+###RUN yum install -y http://ecsft.cern.ch/dist/cvmfs/nightlies/cvmfs-git-854/cvmfs-shrinkwrap-2.6.0-0.854.a2af7fb6d7841ca1git.el7.x86_64.rpm \
+###    http://ecsft.cern.ch/dist/cvmfs/nightlies/cvmfs-git-854/cvmfs-2.6.0-0.854.a2af7fb6d7841ca1git.el7.x86_64.rpm \
+###    && yum clean all
+
+# Allow disabling the cache only from this point onwards if using
+#   docker build -t your-image --build-arg CACHEBUST=$(date +%s) .
+# See https://github.com/moby/moby/issues/1996#issuecomment-185872769
+
+ARG CACHEBUST=1
+
+RUN echo CACHEBUST=$CACHEBUST
+
 COPY ./main.sh /root/
 
 COPY ./generate_Dockerfile.sh /root/