When adapting also log the version jupyter_client is expecting.

It's still (IMHO) unclear how the adaptation goes. Like does "adapting
to protocol X.Y.Z." mean the end-result is X.Y.Z or what you
got is X.Y.Z and it's X.Y.W after adaptation.

notebook/services/kernels/handlers.py

@@ -187,7 +187,7 @@ class ZMQChannelsHandler(AuthenticatedZMQStreamHandler):
         protocol_version = info.get('protocol_version', client_protocol_version)
         if protocol_version != client_protocol_version:
             self.session.adapt_version = int(protocol_version.split('.')[0])
-            self.log.info("Adapting to protocol v%s for kernel %s", protocol_version, self.kernel_id)
+            self.log.info("Adapting to protocol v%s for kernel %s (client expecting %s)", protocol_version, self.kernel_id, client_protocol_version)
         if not self._kernel_info_future.done():
             self._kernel_info_future.set_result(info)