btr_merge(btrn, fn->min_iqs);
length = btr_next_buffer(btrn, &inbuf) & ~(size_t)1;
if (length == 0) { /* eof and 1 byte available */
btr_merge(btrn, fn->min_iqs);
length = btr_next_buffer(btrn, &inbuf) & ~(size_t)1;
if (length == 0) { /* eof and 1 byte available */