On Wed, 29 May 2019 at 19:45, Stefan Monnier <monnier@iro.umontreal.ca>
wrote:

> > Not in detail, it's not an area of expertise of mine. We call
> > (decode-coding-region (point-min) (point-max) 'undecided) on the
> > payload of "https://elpa.gnu.org/packages/archive-contents",
> > which is raw text. The resulting buffer's buffer-file-coding-
> > system is iso-latin-1-dos.
>
> Indeed, it seems that url-insert-file-contents sets
> buffer-file-coding-system.  Maybe we can use that in the emacs-26
> branch.  Can you try the emacs-26 code with the patch below to see if it
> fixes the current problem?
>

Yes, it seems to. At least, there's no error from [M-x
package-list-packages] in emacs -Q.