support empty distributions in both directions

bumble/smp.py

@@ -1014,10 +1014,10 @@ class Session:
             if self.is_responder:
                 # The responder distributes its keys first, the initiator later
                 self.distribute_keys()
-            else:
-                # If we're not expecting key distributions from the peer, we're done
-                if not self.peer_expected_distributions:
-                    self.on_peer_key_distribution_complete()
+
+            # If we're not expecting key distributions from the peer, we're done
+            if not self.peer_expected_distributions:
+                self.on_peer_key_distribution_complete()
 
     def on_connection_encryption_key_refresh(self):
         # Do as if the connection had just been encrypted

tests/self_test.py

@@ -246,8 +246,7 @@ IO_CAP = [
 SC = [False, True]
 MITM = [False, True]
 # Key distribution is a 4-bit bitmask
-# IdKey is necessary for current SMP structure
-KEY_DIST = [i for i in range(16) if (i & SMP_ID_KEY_DISTRIBUTION_FLAG)]
+KEY_DIST = range(16)
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize('io_cap, sc, mitm, key_dist',