conversation: call onDone before announcing to the client

Change-Id: Ib943587e49bcbf16104cf3bbc206e30bc3448f82

src/jamidht/conversation.cpp

@@ -652,10 +652,10 @@ Conversation::sendMessage(const Json::Value& value,
             auto commit = sthis->pimpl_->repository_->commitMessage(
                 Json::writeString(wbuilder, value));
             sthis->clearFetched();
-            sthis->pimpl_->announce(commit);
             lk.unlock();
             if (cb)
                 cb(!commit.empty(), commit);
+            sthis->pimpl_->announce(commit);
         }
     });
 }