bug#19016: 24.4.50; tq.el does the wrong thing when enqueuing inside a callback

[Lars Ingebrigtsen]

Andreas Politz <politza@hochschule-trier.de> writes:

> tq-queue-pop removes the top question and sends the next one.  But here
> a problem occurs, if the callback function adds another question, sends
> it and waits for it's result.  Because this invokes tq-process-buffer
> recursively with the first question still at top.  Resulting in the
> callback to the first question called a second time, third time ... .
>
> Here is a lisp file which should demonstrate this.
>
>
> ..and a patch

Makes sense to me.  I've now applied this to Emacs 27.

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