in tcl_core.c [290:299]
void set_varb(Tcl_Interp* interp, char *var1, char *var2, char *data, int len)
{
Tcl_Obj *obj;
obj = Tcl_NewByteArrayObj(data, len);
if (Tcl_SetVar2Ex(interp, var1, var2, obj, TCL_LEAVE_ERR_MSG) == NULL) {
ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, NULL, "Tcl_SetVarEx2(%s, %s, %s): %s", var1, var2 ? var2 : "NULL", "*data*", Tcl_GetStringResult(interp));
}
}