Trimmed trailing slash in URL provided to create Client API (#15513)

model/client4.go

@@ -116,6 +116,7 @@ func (c *Client4) Must(result interface{}, resp *Response) interface{} {
 }
 
 func NewAPIv4Client(url string) *Client4 {
+	url = strings.TrimRight(url, "/")
 	return &Client4{url, url + API_URL_SUFFIX, &http.Client{}, "", "", map[string]string{}, "", ""}
 }