bug#17425: 24.4.50; tramp-cleanup-this-connection on push-button

[Michael Albinus <michael.albinus@gmx.de>]

Glenn Morris <rgm@gnu.org> writes:

> Michael Albinus wrote:
>
>> (let ((default-directory "http://debbugs.gnu.org/"))
>>   (url-handler-mode 1)
>>   (expand-file-name "17245"))
>
> Hey, this fails with a recursive load in emacs-24.3.90 -Q! :)

So we still have something to fix during the pretest :-)
Reminds me on test case tramp-test33-recursive-load, which I have
written some weeks ago due to a similar error in Tramp.

I'll check tomorrow what's up (but I don't know url-* too much).

>> returns a valid url which could be passed to browse-url.
>
> But surely if it worked it would just return "http://debbugs.gnu.org/17245"?

Yes.

> Why is that a problem?

It's not a problem. It would be a problem, if it does *not* return that
url, when default-directory is changed to something unrelated.

> What does it even mean for browse-url to call eg firefox with a
> default-directory of "http://debbugs.gnu.org/"?
> It surely cannot run firefox on debbugs.gnu.org...

Don't know. Some weeks ago, we have added further schemes to
url-handlers.el, see url-handler-regexp (don't remember whether it was
in the pretest or in trunk). And there is the scheme "ssh", for example.
This would allow to run firefox on a remote host. But I don't know
whether such a url goes ever to browse-url ...

Again, I have no scenario which shows that your patch will fail. But I
have bad feeling to touch default-directory such a way. Experience from
10 years Tramp maintainership.

Best regards, Michael.