[VM] Cached data with international characters

[Uday Reddy]

VM stores in a special header (called X-VM-v5-data) certain internal data
which it remembers between VM sessions.  These are things like the author,
recipients, subject etc., which are primarily used for displaying summary
lines.

The trouble is that message headers can only have ASCII characters but the
data that needs to be remembered can be in other character sets.  Rob F
introduced a way to encode the cached data headers in VM 8.0.10 (way back in
2008).  The release notes say:

    * Correctly store UTF-8 strings in the X-VM-v5-Data header to avoid
      corruption of summary lines. (Thanks to Yuning Feng for reporting)

    * Correctly encode multibyte subjects. (Thanks to Yuning Feng for the
      patch) 

However, I am unable to find any place where this data is being decoded.
So, it is surprising that things stayed this way for so long and nobody
reported any problems!

Are there problems?  Do people that receive messages with international
character sets in the headers find that VM is mishandling them in the
Summary lines?

Cheers,
Uday