Fixed issue where sed buffering (QUIET=1) caused Travis timeout

Makefile

@@ -46,7 +46,7 @@ test: test_format test_dirs test_files test_seek test_truncate \
 test_%: tests/test_%.sh
 
 ifdef QUIET
-	@./$< | sed -n '/^[-=]/p'
+	@./$< | sed -nu '/^[-=]/p'
 else
 	./$<
 endif