Change ListPackets.key to be backwards compatible.

This also adds a new ``ListPackets.encrypted_to`` list, which contains
all the keyids which a message was encrypted to. ``ListPackets.key`` is
just the first one we discovered that it was encrypted to, for backwards
compatibility.

 * FIXES part of Issue #67.
   https://github.com/isislovecruft/python-gnupg/issues/67

 * CHANGES the additions made in commit f70a7dc4f0 by @tomgalloway in
   PR#70 to be backwards compatible.
   f70a7dc4f0
   https://github.com/isislovecruft/python-gnupg/pull/77

gnupg/_parsers.py

@@ -1512,8 +1512,12 @@ class ListPackets(object):
         self.need_passphrase_sym = None
         #: The keyid and uid which this data is encrypted to.
         self.userid_hint = None
+        #: The first key that we detected that a message was encrypted
+        #: to. This is provided for backwards compatibility. As of Issue #77_,
+        #: the ``encrypted_to`` attribute should be used instead.
+        self.key = None
         #: A list of keyid's that the message has been encrypted to.
-        self.key = []
+        self.encrypted_to = []
 
     def _handle_status(self, key, value):
         """Parse a status code from the attached GnuPG process.
@@ -1523,8 +1527,10 @@ class ListPackets(object):
         if key == 'NODATA':
             self.status = nodata(value)
         elif key == 'ENC_TO':
-            key_to_add, _, _ = value.split()
-            self.key.append(key_to_add)
+            key, _, _ = value.split()
+            if not self.key:
+                self.key = key
+            self.encrypted_to.append(key)
         elif key == 'NEED_PASSPHRASE':
             self.need_passphrase = True
         elif key == 'NEED_PASSPHRASE_SYM':

gnupg/test/test_gnupg.py

@@ -918,7 +918,7 @@ authentication."""
         ## We expect Alice's key to be hidden (returned as zero's) and Bob's 
         ## key to be there.
         expected_values = ["0000000000000000", "E0ED97345F2973D6"]
-        self.assertEquals(expected_values, self.gpg.list_packets(encrypted).key)
+        self.assertEquals(expected_values, self.gpg.list_packets(encrypted).encrypted_to)
 
     def test_encryption_throw_keyids(self):
         """Test to ensure throw-keyids=True causes all recipients to be hidden.
@@ -957,7 +957,7 @@ boolean circuit causes a considerable overhead."""
         ## We expect Alice's key to be hidden (returned as zero's) and Bob's
         ## key to be there.
         expected_values = ["0000000000000000", "0000000000000000"]
-        self.assertEquals(expected_values, self.gpg.list_packets(encrypted).key)
+        self.assertEquals(expected_values, self.gpg.list_packets(encrypted).encrypted_to)
 
     def test_encryption_decryption_multi_recipient(self):
         """Test decryption of an encrypted string for multiple users"""