#1693546: don't add quotes around RFC 2231 encoded values.

The RFC is bit hard to understand on this point, but the examples
clearly show that parameter values that are encoded according
to its charset/language rules don't have surrounding quotes, and
the ABNF does not allow for quotes.  So when we produce such
encoded values, we no longer add quotes.
diff --git a/Lib/email/test/test_email.py b/Lib/email/test/test_email.py
index 53c4042..73ac347 100644
--- a/Lib/email/test/test_email.py
+++ b/Lib/email/test/test_email.py
@@ -534,7 +534,7 @@
         msg.add_header('Content-Disposition', 'attachment',
             filename="Fußballer.ppt")
         self.assertEqual(
-            'attachment; filename*="utf-8\'\'Fu%C3%9Fballer.ppt"',
+            'attachment; filename*=utf-8\'\'Fu%C3%9Fballer.ppt',
             msg['Content-Disposition'])
 
     def test_nonascii_add_header_via_triple(self):
@@ -542,7 +542,23 @@
         msg.add_header('Content-Disposition', 'attachment',
             filename=('iso-8859-1', '', 'Fußballer.ppt'))
         self.assertEqual(
-            'attachment; filename*="iso-8859-1\'\'Fu%DFballer.ppt"',
+            'attachment; filename*=iso-8859-1\'\'Fu%DFballer.ppt',
+            msg['Content-Disposition'])
+
+    def test_ascii_add_header_with_tspecial(self):
+        msg = Message()
+        msg.add_header('Content-Disposition', 'attachment',
+            filename="windows [filename].ppt")
+        self.assertEqual(
+            'attachment; filename="windows [filename].ppt"',
+            msg['Content-Disposition'])
+
+    def test_nonascii_add_header_with_tspecial(self):
+        msg = Message()
+        msg.add_header('Content-Disposition', 'attachment',
+            filename="Fußballer [filename].ppt")
+        self.assertEqual(
+            "attachment; filename*=utf-8''Fu%C3%9Fballer%20%5Bfilename%5D.ppt",
             msg['Content-Disposition'])
 
 
@@ -3643,7 +3659,7 @@
 Subject: This is a test message
 Date: Fri, 4 May 2001 14:05:44 -0400
 Content-Type: text/plain; charset=us-ascii;
- title*="us-ascii'en'This%20is%20even%20more%20%2A%2A%2Afun%2A%2A%2A%20isn%27t%20it%21"
+ title*=us-ascii'en'This%20is%20even%20more%20%2A%2A%2Afun%2A%2A%2A%20isn%27t%20it%21
 
 
 Hi,
@@ -3673,7 +3689,7 @@
 Subject: This is a test message
 Date: Fri, 4 May 2001 14:05:44 -0400
 Content-Type: text/plain; charset="us-ascii";
- title*="us-ascii'en'This%20is%20even%20more%20%2A%2A%2Afun%2A%2A%2A%20isn%27t%20it%21"
+ title*=us-ascii'en'This%20is%20even%20more%20%2A%2A%2Afun%2A%2A%2A%20isn%27t%20it%21
 
 
 Hi,
@@ -3688,6 +3704,32 @@
         msg = self._msgobj('msg_32.txt')
         eq(msg.get_content_charset(), 'us-ascii')
 
+    def test_rfc2231_parse_rfc_quoting(self):
+        m = textwrap.dedent('''\
+            Content-Disposition: inline;
+            \tfilename*0*=''This%20is%20even%20more%20;
+            \tfilename*1*=%2A%2A%2Afun%2A%2A%2A%20;
+            \tfilename*2="is it not.pdf"
+
+            ''')
+        msg = email.message_from_string(m)
+        self.assertEqual(msg.get_filename(),
+                         'This is even more ***fun*** is it not.pdf')
+        self.assertEqual(m, msg.as_string())
+
+    def test_rfc2231_parse_extra_quoting(self):
+        m = textwrap.dedent('''\
+            Content-Disposition: inline;
+            \tfilename*0*="''This%20is%20even%20more%20";
+            \tfilename*1*="%2A%2A%2Afun%2A%2A%2A%20";
+            \tfilename*2="is it not.pdf"
+
+            ''')
+        msg = email.message_from_string(m)
+        self.assertEqual(msg.get_filename(),
+                         'This is even more ***fun*** is it not.pdf')
+        self.assertEqual(m, msg.as_string())
+
     def test_rfc2231_no_language_or_charset(self):
         m = '''\
 Content-Transfer-Encoding: 8bit