Replace @@plpythonu@@ var in old_versions

client/Makefile

@@ -96,6 +96,9 @@ devclean:
 	rm -f $(NEW_EXTENSION_ARTIFACT)
 	rm -f $(GENERATED_SQL_FILES)
 	rm -rf $(TEST_DIR)
+	for f in $(OLD_VERSIONS); do \
+		mv $${f}.bak $${f} || true; \
+	done
 
 # If needed remove PARALLEL tags from the release files
 release_remove_parallel_deploy:
@@ -122,6 +125,11 @@ replace_variables:
 		sed -e 's/@@plpythonu@@/$(PLPYTHONU)/g' \
 		>> $(TEST_DIR)/expected/$${f}.out; \
 	done
+	for f in $(OLD_VERSIONS); do \
+		mv $${f}.bak $${f} || true; \
+		sed --in-place=.bak -e 's/@@plpythonu@@/$(PLPYTHONU)/g' $${f}; \
+		echo "sed --in-place=.bak -e 's/@@plpythonu@@/$(PLPYTHONU)/g' $${f}"; \
+	done
 
 # Install the current release into the PostgreSQL extensions directory
 deploy: release_remove_parallel_deploy