Re: Bug in 9.5.3 org--file-default-apps

[Max Nikulin <manikulin@gmail.com>]

On 21/05/2022 08:44, Ihor Radchenko wrote:
> Max Nikulin writes:
> 
>> It is the same with and without -Q and no, I have not customized
>> `mailcap-user-mime-data', its value is nil, easy customization interface
>> tells that it is the standard value. There is a chance that debian has
>> some patch, but most of debian specific is disabled when -Q option is used.
> 
> Interesting. In any case, it confirms that mailcap behaviour depends on
> both Emacs settings and also system settings.

You should be even more surprised, if I say that [[file:~/tstorg]] link 
is opened in emacs buffer in shell-script mode (emacs-27.1, org main 
HEAD) despite

    (mailcap-mime-info nil)
    nil

actually it is a minimal LXC container with no mime-support package 
installed, so /etc/mailcap file is absent.

Notice `mailcap-mime-data' has the following entries for a long time
     ("text"
      ("plain"
       (viewer  . view-mode)
       (type    . "text/plain"))
      ("plain"
       (viewer  . fundamental-mode)
       (type    . "text/plain"))

The source of the problem is that Emacs-27 was released with the 
following bug:

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=40247
mailcap-mime-data erased when parsing mime parts

So `mailcap-parse-mailcaps' called from `mailcap-mime-info' erases 
predefined associations in Emacs-27.