Final results aren't saved in `--directory` when `--sample_hyper` is "yes" with some `--random_seed` values and datasets

[rtrad89]

I encountered that with some datasets, the final results of the training phase aren't stored under --directory if I use a random_seed of 13712 while hyper-sampling the concentration parameters as well. Only the file state.log would be produced, but not any other output files.

To reproduce the problem:

1. Download this training corpus from PAN @ CLEF 2017 competition
2. Run the regular hdp (not the fast variant) on the LDA-C corpus of the fifth training problem set, like:

hdp.exe --data ..\pan17_train\problem005\ldac_corpus.dat --algorithm train --directory ..\output --sample_hyper yes --save_lag -1 --random_seed 13712

(I used gensim to generate the LDA-C corpora)

The program will run smoothly and no error would be raised. However, the output directory would contain only the state.log file and the interim outputs, where we expect also mode.bin, mode-topics.dat and mode-word-assignments.dat. As far as I can tell, the combination of --sample_hyper yes and --random_seed 13712 is causing this fault to occur on selected datasets.