Fix for bug #1634343: allow specifying empty arguments on Windows

Lib/subprocess.py

@@ -499,7 +499,7 @@ def list2cmdline(seq):
         if result:
             result.append(' ')
 
-        needquote = (" " in arg) or ("\t" in arg)
+        needquote = (" " in arg) or ("\t" in arg) or arg == ""
         if needquote:
             result.append('"')
 

Lib/test/test_subprocess.py

@@ -430,6 +430,8 @@ class ProcessTestCase(unittest.TestCase):
                          '"a\\\\b c" d e')
         self.assertEqual(subprocess.list2cmdline(['a\\\\b\\ c', 'd', 'e']),
                          '"a\\\\b\\ c" d e')
+        self.assertEqual(subprocess.list2cmdline(['ab', '']),
+                         'ab ""')
 
 
     def test_poll(self):