fixup! add Trott's suggestion

test/common/README.md

@@ -952,7 +952,7 @@ listener to process `'beforeExit'`. If a file needs to be left open until
 Node.js completes, use a child process and call `refresh()` only in the
 parent.
 
-It is usually only necessary to call `refresh()` once in a test file. 
+It is usually only necessary to call `refresh()` once in a test file.
 Avoid calling it more than once in an asynchronous context as one call
 might refresh the temporary directory of a different context, causing
 the test to fail somewhat mysteriously.