commands/http: Fixed client panic when sending a Request with nil 'Files'

http/client.go

@@ -48,14 +48,21 @@ func (c *client) Send(req cmds.Request) (cmds.Response, error) {
 	}
 
 	var fileReader *MultiFileReader
+	var reader io.Reader
+
 	if req.Files() != nil {
 		fileReader = NewMultiFileReader(req.Files(), true)
+		reader = fileReader
+	} else {
+		// if we have no file data, use an empty Reader
+		// (http.NewRequest panics when a nil Reader is used)
+		reader = strings.NewReader("")
 	}
 
 	path := strings.Join(req.Path(), "/")
 	url := fmt.Sprintf(ApiUrlFormat, c.serverAddress, ApiPath, path, query)
 
-	httpReq, err := http.NewRequest("POST", url, fileReader)
+	httpReq, err := http.NewRequest("POST", url, reader)
 	if err != nil {
 		return nil, err
 	}