Valgrind's wine_cp_wcstombs warnings

Hi,

running the MCI tests with Valgrind generates a lot of output like follows

==13170== Use of uninitialised value of size 4
==13170==    at 0x4035369: wine_cp_wcstombs (wctomb.c:147)
...[every line from 148 to 161]
==13170== Use of uninitialised value of size 4
==13170==    at 0x403550A: wine_cp_wcstombs (wctomb.c:162)

I suspect the A<->W mapping is still not fully correct (I know at
least one more case, but I'm not sure it gets triggered by the tests)
but perhaps it's also the W->UNIX.UTF-8 conversions internal to Wine
which cause these hits.  How do I tell?

Is there any way to get more precise reporting for the above messages
(e.g. a backtrace)?  The present output is not helpful at identifying
the origin of the uninitialised read.

Perhaps Valgrind is broken? Why does it mention "size 4" when all
access in the offending function is either "char *" or "short *"
according to the source
http://source.winehq.org/source/libs/wine/wctomb.c#L145 ?

Thanks for your help,
    Jörg Höhle