Index: Lib/test/test_subprocess.py
===================================================================
--- Lib/test/test_subprocess.py	(révision 81394)
+++ Lib/test/test_subprocess.py	(copie de travail)
@@ -535,7 +535,18 @@
             if c.exception.errno != 2:  # ignore "no such file"
                 raise c.exception
 
+    def test_issue8780(self):
+        # Ensure that stdout if inherited from the parent
+        # if stdout=PIPE is not used
+        code = ';'.join((
+            'import subprocess, sys',
+            'retcode = subprocess.call('
+                "[sys.executable, '-c', 'print(\"Hello World!\")'])",
+            'assert retcode == 0'))
+        output = subprocess.check_output([sys.executable, '-c', code])
+        self.assert_(output.startswith(b'Hello World!'), ascii(output))
 
+
 # context manager
 class _SuppressCoreFiles(object):
     """Try to prevent core files from being created."""
Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(révision 81394)
+++ Lib/subprocess.py	(copie de travail)
@@ -843,7 +843,7 @@
             # Process startup details
             if startupinfo is None:
                 startupinfo = STARTUPINFO()
-            if None not in (p2cread, c2pwrite, errwrite):
+            if -1 not in (p2cread, c2pwrite, errwrite):
                 startupinfo.dwFlags |= _subprocess.STARTF_USESTDHANDLES
                 startupinfo.hStdInput = p2cread
                 startupinfo.hStdOutput = c2pwrite