[BUG] CircomUtxo and Utxo commitments occasionally mismatch

[drewstone]

Describe the bug

  1) Utxo Class
       CircomUtxo and Utxo should generate compatible outputs private utxo:

      AssertionError: expected Uint8Array[ 13, 175, 50, 131, …(-138) ] to deeply equal Uint8Array[ 218, 243, 40, 58, …(-158) ]
      + expected - actual

      -{"0":13,"1":175,"2":50,"3":131,"4":171,"5":252,"6":132,"7":110,"8":98,"9":252,"10":242,"11":244,"12":139,"13":131,"14":79,"15":209,"16":15,"17":217,"18":46,"19":84,"20":97,"21":229,"22":233,"23":135,"24":55,"25":163,"26":180,"27":251,"28":192,"29":73,"30":208,"31":164}
      +{"0":218,"1":243,"2":40,"3":58,"4":191,"5":200,"6":70,"7":230,"8":47,"9":207,"10":47,"11":72,"12":184,"13":52,"14":253,"15":16,"16":253,"17":146,"18":229,"19":70,"20":30,"21":94,"22":152,"23":115,"24":122,"25":59,"26":79,"27":188,"28":4,"29":157,"30":10,"31":64}

To Reproduce
Steps to reproduce the behavior:

1. Run tests repeatedly until failure.

Expected behavior
Commitments should be equivalent.