Extra backslashes

main.mk

@@ -44,7 +44,7 @@ include $(LIBDIR)/update.mk
 .includes.mk: $(filter %.md,$(drafts_source))
 	@rm -f $@
 	@for d in $^; do \
-	  for f in $$(sed -e $$'s/^{::include\(-nested\)* \(.*\)}$$/\2/;t\nd' "$$d"); do \
+	  for f in $$(sed -e $$'s/^{::include\\(-nested\\)* \\(.*\\)}$$/\\2/;t\nd' "$$d"); do \
 	    echo "$${d%.md}.xml: $$f" >> $@; \
 	  done; \
 	done