force save version when doc is unchanged

src/app_dialogs.cpp

@@ -340,6 +340,7 @@ void App::dialog_save_ver()
 
     doc_name = next;
     doc_path = doc_dir + "/" + next + ".ppi";
+    canvas->m_canvas->m_unsaved = true;
     title_update();
     canvas->m_canvas->project_save(doc_path);
 }