Candidate search mutates input

[backus]

>> candidate = BlockScore::Candidate.retrieve('55de4b136437350003000013')
=> #<BlockScore::Candidate:0x3fe396c419b8 JSON: {
  "object": "candidate",
  "id": "55de4b136437350003000013",
  "created_at": 1440631571,
  "updated_at": 1440631586,
  "livemode": false,
  "note": null,
  "ssn": null,
  "passport": null,
  "date_of_birth": null,
  "name_first": "RunScopeEdited",
  "name_middle": null,
  "name_last": "Test",
  "address_street1": null,
  "address_street2": null,
  "address_city": null,
  "address_subdivision": null,
  "address_postal_code": null,
  "address_country_code": null,
  "deleted": true
}
>> constraints = { similarity_threshold: 0.8 }
=> {
  :similarity_threshold => 0.8
}
>> candidate.search(constraints)
=> []
>> constraints
=> {
          :candidate_id => "55de4b136437350003000013",
  :similarity_threshold => 0.8
}