Why does `goc run agentport` not take effect

In file `cmd/run.go` 
```
ci := &cover.CoverInfo{
    ...
    AgentPort:                "",
    ...
}
```
Small change to:
```
ci := &cover.CoverInfo{
    ...
    AgentPort:               agentPort.String(),
    ...
}
```
In this way, the port number can be fixed during debugging.