bug#20159: 24.4; url-retrieve invokes same callback twice with kill-buffer

[Lars Ingebrigtsen <larsi@gnus.org>]

Christopher Wellons <wellons@nullprogram.com> writes:

>     ;;; -*- lexical-binding: t; -*-
>     (let ((calls 0))
>       (url-retrieve "http://localhost:1/"
>                     (lambda (_)
>                       (assert (= 1 (cl-incf calls)))
>                       (kill-buffer))))
>
> When I eval the above expression, the assertion fails asynchronously.
>
>     error in process sentinel: Assertion failed: (= 1 (cl-incf calls))

Eli fixed something related to this, but the bug still remains.  I used
this version:

;;; -*- lexical-binding: t; -*-
(let ((calls 0))
  (url-retrieve "http://localhost:1/"
                (lambda (status)
		  (message "%s '%s'" calls status)
                  (assert (= 1 (cl-incf calls)))
		  (kill-buffer))))

These are the messages:

Contacting host: localhost:1
#<buffer  *http localhost:1*-537967>
0 ’(:error (error connection-failed failed with code 111
 :host localhost :service 1))’
1 ’(:error (error connection-failed deleted
 :host localhost :service 1) :error (error connection-failed failed with code 111
 :host localhost :service 1))’

The second message is...  pretty weird...

Anybody have a guess why this happens?

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   bloggy blog: http://lars.ingebrigtsen.no