bug#9575: 23.3; M-x describe-coding-system and auto-coding-alist not used

[Jari Aalto]

In GNU Emacs 23.3.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.4)
 of 2011-04-10 on brahms, modified by Debian

Calling:

    C-h C RET  (M-x describe-coding-system)

Brings up information about, amongst other things:

    Particular coding systems specified for certain file names:

    OPERATION   TARGET PATTERN          CODING SYSTEM(s)
    ---------   --------------          ----------------
    File I/O    "\\.gpg\\'"             (no-conversion . no-conversion)
    ...

PROBLEM

If I understand correct, this listing reflects the values of
file-coding-system-alist.

The shown listing is not correct, because it doesn't consider:

    auto-coding-alist's value is shown below.
    ...
    The settings in this alist take priority over `coding:' tags
    in the file (see the function `set-auto-coding')
    and the contents of `file-coding-system-alist'.

Jari