Don't set client to nil when closing broker

[jwilder]

Fixes 2352

[otoolep]

This kind of makes sense. Really, isn't the broker type missing an Open call, which should be called before the broker type is used? This seems to be just changing how Close works, when what is missing the Open. Or am I missing something?

[otoolep]

To be clear, in Open the client would be set to non-nil, it seems to me. This seems a fix to allow a broker object to be re-used after Close() has been called, but that would indicate a broken API. Make sense?

[jwilder]

The client is already created and set when the broker is created here: https://github.com/influxdb/influxdb/blob/master/broker.go#L47

This nil pointer is in the http.Client here: https://github.com/golang/go/blob/release-branch.go1.4/src/net/http/client.go#L304

Since we're using the DefaultTransport and http.Client are supposed to be reused, setting it to nil doesn't make sense.

[otoolep]

OK, very good -- thanks @jwilder . That was the context I was missing.

+1