use of input reserve - gr trellis

[guruofquality]

notes in comment from gr_block.cc:

void gr_block::_update_input_reserve(void)
{
    /*!
     * Set an input reserve for fixed rate blocks.
     *
     * FIXME: Also do this when output multiple is large,
     * This makes gr-trellis pass under conditions where not fixed rate set,
     * but the output multiple is so large that default input isnt sufficient.
     */
    if (_enable_fixed_rate or _output_multiple_items > 1024)
    {
        gras::InputPortConfig config = this->input_config();
        config.reserve_items = size_t(0.5 + _output_multiple_items/_relative_rate);
        if (config.reserve_items) this->set_input_config(config);
    }
}

[guruofquality]

Still an issue, here is the verbose if we remove the hack-around:

gnuradio/gr-trellis/src/python/qa_trellis_test.sh 
Created default thread pool with 8 threads.
terminate called after throwing an instance of 'std::runtime_error'
  what():  input_fail called on maximum_items buffer
Aborted (core dumped)