Save project after opening

editor/editor_node.cpp

@@ -592,6 +592,9 @@ void EditorNode::_notification(int p_what) {
 				_editor_select(EDITOR_3D);
 			}
 
+			// Save the project after opening to mark it as last modified.
+			ProjectSettings::get_singleton()->save();
+
 			/* DO NOT LOAD SCENES HERE, WAIT FOR FILE SCANNING AND REIMPORT TO COMPLETE */
 		} break;