Can't set debug port by specifying --node-args="--debug=7001"

```
pm2 start main.js --node-args="--debug=7001"
```

When running the above cli command, the node process does receive the "--debug" argument, but ignores the port. The console responds:

```
Debugger listening on port 5863
```

I am assuming port #5863 is just a default selected by node. Any ideas why the port isn't getting set?
