Strange character set reported in TUTORIAL

[Eli Zaretskii]

Today's CVS trunk on MS-Windows, font backend disabled:

  emacs -Q
  C-u C-h t Russian RET

Now go to any Cyrillic letter and type "C-u C-x =".  Surprisingly, I
see this:

          character: Д (1044, #o2024, #x414)
  preferred charset: gb18030 (GB18030)
         code point: 0xA7A5
             syntax: w  which means: word
           category: Y:Cyrillic characters of 2-byte character sets c:Chinese
                     h:Korean j:Japanese y:Cyrillic
        buffer code: #xD0 #x94
          file code: #xE4 (encoded by coding system cyrillic-koi8-unix)
            display: by this font (glyph code)
       -outline-Courier New-normal-r-normal-normal-13-97-96-96-c-*-koi8-r 
(#x414)

For comparison, Emacs 22.1 says this:

  character: Д (3636, #o7064, #xe34, U+0414)
    charset: cyrillic-iso8859-5
             (Right-Hand Part of Latin/Cyrillic Alphabet (ISO/IEC 8859-5): 
ISO-IR-144.)
 code point: #x34
     syntax: w  which means: word
   category: y:Cyrillic
buffer code: #x8C #xB4
  file code: #xE4 (encoded by coding system cyrillic-koi8-unix)
    display: by this font (glyph code)
     -outline-Courier New-normal-r-normal-normal-13-97-96-96-c-*-iso8859-5 
(#x414)

This isn't limited to Cyrillic scripts in any way: I see similar
display with other non-ASCII characters, such as Latin-1, including in
etc/HELLO: they all claim GB18030 as preferred charset and mention CJK
character sets in the category: line.

If this is a feature, can someone explain it?