I've narrowed it down to the #ifdef USE_JAPANESEUTF8_SUPPORT section that begins at line 943 of UCdomap.c.
rc = (int) iconv(cd, (ICONV_CONST char **) &pin, &inleft, &pout,
&outleft);
is the command that sets the eventual returned value. So recruiting
inconv support to handle Japanese characters has had this side-effect.
russell bell
