AV1: av1src doesn't support equal picture interval being specified with timing info, but without decoder model info

Section E.3.1 of the AV1 specification states that:
To use Resource Availability mode, the following parameters should be set in the encoded video bitstream:
• timing_info_present_flag equal to 1
• decoder_model_info_present_flag equal to 0
• equal_picture_interval equal to 1

and

Section E.3.2 of the AV1 specification states that:
To use Decoding Schedule Mode, the following parameters should be signaled by the encoded video bitstream:
• timing_info_present_flag equal to 1
• decoder_model_info_present_flag equal to 1
• decoder_model_present_for_this_op[ op ] equal to 1

However consider a stream with timing_info_present_flag==1 && decoder_model_info_present_flag==0 && equal_picture_interval==0, implying that no neither Decoder Model mode is active.

However, av1src will consider this as Resource Availability mode:

   // Work out which decoder model mode is in use
    decoder_model_mode = (decoder_model_info_present_flag ?
                          DECODER_MODEL_SCHEDULE :
                          DECODER_MODEL_RESOURCE_AVAILABILITY)

And then this assertion will fire:

    // The av1src encoder and decoder both assume that a stream with
    // non-equal picture interval has decoder model info and operates
    // in DECODER_MODEL_SCHEDULE mode. This isn't guaranteed by the
    // spec, but it's all we support.
    if (timing_info_present &&
        (decoder_model_mode == DECODER_MODEL_RESOURCE_AVAILABILITY)) {
      ASSERT (equal_picture_interval,
              "av1src only supports equal picture interval without decoder model info.")
    }