Revert r60115

This revision introduced quoting for strings containing | based
on a misunderstanding of the commonly used quoting rules used
on Windows.

| is interpreted by cmd.exe, not by the MS C runtime argv initializer.
It only needs to be quoted if it is part of an argument passed through
cmd.exe.

See issue1300, issue7839, and issue8972.

Lib/test/test_subprocess.py

@@ -486,8 +486,6 @@ def test_list2cmdline(self):
                          '"a\\\\b\\ c" d e')
         self.assertEqual(subprocess.list2cmdline(['ab', '']),
                          'ab ""')
-        self.assertEqual(subprocess.list2cmdline(['echo', 'foo|bar']),
-                         'echo "foo|bar"')
 
 
     def test_poll(self):