No longer raise error on HTTP 402 (Payment Required) (bug#81101)

* lisp/url/url-http.el (url-http-parse-headers): Return t instead of
raising an error, to give the user a chance to interact with the page.

lisp/url/url-http.el

@@ -826,9 +826,12 @@ should be shown to the user."
                 ;; Authorization header field.
                 (url-http-handle-authentication nil))
                ('payment-required              ; 402
-                ;; This code is reserved for future use
-                (url-mark-buffer-as-dead buffer)
-                (error "Somebody wants you to give them money"))
+                ;; This code is "reserved for future use", but in the
+                ;; mean time websites have been seen to use it, for
+                ;; instance anti-bot challenges requiring the "payment"
+                ;; of a click of a button to prove the visitor is human,
+                ;; so we no longer raise an `error' here.
+                t)
                ('forbidden			; 403
                 ;; The server understood the request, but is refusing to
                 ;; fulfill it.  Authorization will not help and the request