Client: always call ensureReaderClosed

Unlike a plain `net/http/client.Do()`, requests made through client/request
use the `sendRequest` function, which parses the server response, and may
convert non-transport errors into errors (through `cli.checkResponseErr()`).

This means that we cannot assume that no reader was opened if an error is
returned.

This patch changes various locations where `ensureReaderClosed` was only
called in the non-error situation, and uses a `defer` to make sure it's
always called.

`ensureReaderClosed` itself already checks if the response's body was set,
so in situations where the error was due to a transport error, calling
`ensureReaderClosed` should be a no-op.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/plugin_inspect.go

@@ -15,11 +15,11 @@ func (cli *Client) PluginInspectWithRaw(ctx context.Context, name string) (*type
 		return nil, nil, objectNotFoundError{object: "plugin", id: name}
 	}
 	resp, err := cli.get(ctx, "/plugins/"+name+"/json", nil, nil)
+	defer ensureReaderClosed(resp)
 	if err != nil {
 		return nil, nil, wrapResponseError(err, resp, "plugin", name)
 	}
 
-	defer ensureReaderClosed(resp)
 	body, err := ioutil.ReadAll(resp.body)
 	if err != nil {
 		return nil, nil, err