fix the incorrect test

IV/Makefile

@@ -27,9 +27,10 @@ clean:
 
 .PHONY: clean-tables
 clean-tables:
-	for t in $$(./db -c '\dt' | awk '/demo|debug|integ/{print $$3}'); do \
+	for t in $$(./db -c '\dt' | awk '/\y(demo_wm|debug_wm|figures)\y/{print $$3}'); do \
 		./db -c "drop table $$t"; \
 	done
+	-rm .faux_test
 
 .PHONY: slides
 slides: $(SLIDES)