Without passing an empty argument list to `emqx_ctl:print`, formatting
instructions like `~n` are being printed literally.
```
Ignore.~nJoin the cluster successfully.~nCluster status: #{running_nodes =>
['emqx@emqx-0.int.thalesmg','emqx@emqx-1.int.thalesmg',
'emqx@emqx-2.int.thalesmg','emqx@emqx-3.int.thalesmg',
'emqx@emqx-4.int.thalesmg'],
stopped_nodes => []}
```
JianBo He