fix "BytesWarning: str() on a bytes instance"

diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index adf00a50a0784e01a22ad89311bebc542cd7a99c..a633af5058071157bfbef56227d94454dcf64dd8 100644 (file)
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -801,7 +801,8 @@ class ProcessTestCase(BaseTestCase):
                                  stdout=subprocess.PIPE, stderr=subprocess.PIPE)
             stdout, stderr = p.communicate()
             self.assertEqual(0, p.returncode, "sigchild_ignore.py exited"
-                             " non-zero with this error:\n%s" % stderr)
+                             " non-zero with this error:\n%s" %
+                             stderr.decode('utf8'))
 
 
     #