bindings/python-cffi: add matched property to message objects

Existing users of the legacy python bindings use
message.get_flags(Message.FLAG.MATCH) to determine which messages in a
thread matched. Since the bindings don't provide get_flags anymore,
they should provide a property analogous to the existing "excluded"
property.

bindings/python-cffi/notmuch2/_message.py

@@ -205,6 +205,20 @@ class Message(base.NotmuchObject):
             self._msg_p, capi.lib.NOTMUCH_MESSAGE_FLAG_EXCLUDED)
         return bool(ret)
 
+    @property
+    def matched(self):
+        """Indicates whether this message was matched by the query.
+
+        When a thread is created from a search, some of the
+        messages may not match the original query.  This property
+        is set to *True* for those that do match.
+
+        :raises ObjectDestroyedError: if used after destroyed.
+        """
+        ret = capi.lib.notmuch_message_get_flag(
+            self._msg_p, capi.lib.NOTMUCH_MESSAGE_FLAG_MATCH)
+        return bool(ret)
+
     @property
     def date(self):
         """The message date as an integer.

bindings/python-cffi/tests/test_message.py

@@ -97,6 +97,9 @@ class TestMessage:
     def test_ghost_no(self, msg):
         assert not msg.ghost
 
+    def test_matched_no(self,msg):
+        assert not msg.matched
+
     def test_date(self, msg):
         # XXX Someone seems to treat things as local time instead of
         #     UTC or the other way around.

bindings/python-cffi/tests/test_thread.py

@@ -57,6 +57,13 @@ def test_iter(thread):
 def test_matched(thread):
     assert thread.matched == 1
 
+def test_matched_iter(thread):
+    count = 0
+    msgs = list(iter(thread))
+    for msg in msgs:
+        if msg.matched:
+            count += 1
+    assert count == thread.matched
 
 def test_authors_type(thread):
     assert isinstance(thread.authors, notmuch2.BinString)