http://cvs.winehq.org/cvsweb/wine/dlls/msvcrt/file.c.diff?r1=1.59&r2=1.60&f=h

It has a one line changlog saying:
Duplicate stdin/stdout handles to avoid closing them when library is
unloaded.

If I revert file.c to pre-patch state, redirection works fine. But
am not sure if there will be unexpected consequences. So I searched
the wine-patch and wine-devel archives but didn't find the patch or
 any discussion about it.

Could someone explain what exactly that changelog line means?

A simple test
 program
------------------------------------------------------------------------
#include "stdio.h"
#include "process.h"

int main(int argc, char* argv[])
{
    if( argc == 1 )
    {
        char *argv2[] = { argv[0], "foo", NULL };
        _spawnv(_P_NOWAIT, argv[0], argv2);
    }
    else
    {
        puts("This won't print with builtin msvcrt");
    }
    return 0;
}