Fix 'undefined local variable or method `pid` for #<Puma::ControlCLI:0x007f185fcef968>' when execute pumactl with `--pid` option.
Fix 'undefined local variable or method `pid` for #<Puma::ControlCLI:0x007f185fcef968>' when execute pumactl with `--pid` option.

```
bundle exec pumactl --pid tmp/pids/puma.pid stop
undefined local variable or method `pid' for #<Puma::ControlCLI:0x007f185fcef968>
Did you mean?  @pid
```

prathamesh-sonpatki/puma,looker/puma,puma/puma,respire/puma,looker/puma,prathamesh-sonpatki/puma,eileencodes/puma,kyledrake/puma,kyledrake/puma,prathamesh-sonpatki/puma,looker/puma,eileencodes/puma,kyledrake/puma,kyledrake/puma,puma/puma,eileencodes/puma,puma/puma,puma/puma,eileencodes/puma,respire/puma,unleashed/puma,ngpestelos/puma,unleashed/puma,ngpestelos/puma,ngpestelos/puma,respire/puma,ngpestelos/puma,looker/puma,respire/puma,prathamesh-sonpatki/puma,unleashed/puma,unleashed/puma