fix: gc and duplicate detection

containers/jug/dev.Dockerfile

@@ -207,6 +207,12 @@ RUN --mount=type=cache,target=/var/cache/spack                          \
     <<EOF
 make --jobs ${jobs} --keep-going --directory /opt/spack-environment \
   SPACK_ENV=${SPACK_ENV} SPACK_INSTALL_FLAGS="--use-buildcache only"
+spack gc --yes-to-all
+spack find --long --no-groups \
+| sed -e '1,/Installed packages/d;s/\([^@]*\).*/\1/g' \
+| uniq -D -f1 | grep -v -w -e "\(epic\|py-pip\|py-cython\)" \
+| tee /tmp/duplicates.txt
+test -s /tmp/duplicates.txt && ( cat /tmp/duplicates.txt | while read hash spec ; do spack spec --long /${hash} ; done ) && exit 1
 EOF
 
 ## Create views at /opt/local and /opt/detector