Index: clang-tools-extra/trunk/clang-tidy/tool/run-clang-tidy.py
===================================================================
--- clang-tools-extra/trunk/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/trunk/clang-tidy/tool/run-clang-tidy.py
@@ -172,6 +172,7 @@
     with lock:
       sys.stdout.write(' '.join(invocation) + '\n' + output.decode('utf-8') + '\n')
       if len(err) > 0:
+        sys.stdout.flush()
         sys.stderr.write(err.decode('utf-8') + '\n')
     queue.task_done()