don't remove things in update_deps then?

Dockerfile

@@ -62,7 +62,8 @@ ENV SWIG_FEATURES="-D__x86_64__"
 # Install all python requires
 RUN mkdir -p /deps/{build,cache,src}/ && \
     ln -s /code/package.json /deps/package.json && \
-    make update_deps
+    make update_deps && \
+    rm -rf /deps/build/ /deps/cache/
 
 # Preserve bash history across image updates.
 # This works best when you link your local source code

Makefile-docker

@@ -111,7 +111,6 @@ copy_node_js:
 	for dest in $(NODE_LIBS_JQUERY_UI) ; do cp $(NODE_MODULES)$$dest $(STATIC_JQUERY_UI) ; done
 
 update_deps: install_python_dependencies install_node_dependencies
-	rm -rf /deps/build/ /deps/cache/
 
 update_db:
 	schematic src/olympia/migrations