Example:
green step: https://build.chromium.org/p/tryserver.chromium.perf/builders/win_8_perf_bisect/builds/2042/steps/buildbucket.get%20%285%29/

Output (notice result and failure_reason:
{
  "build": {
    "bucket": "master.tryserver.chromium.perf", 
    "completed_ts": "1468768218843400", 
    "created_by": "user:446450136466-ugqfr4djan52mqrm39lernfnho0lafi5@developer.gserviceaccount.com", 
    "created_ts": "1468764106413730", 
    "failure_reason": "INFRA_FAILURE", 
    "id": "9006882924416517104", 
    "parameters_json": "{\"builder_name\": \"win_perf_bisect_builder\", \"properties\": {\"build_archive_url\": \"gs://chrome-perf-tryjob/Win Builder/full-build-win32_d1a7457666ee116f4500cc7c1e69bff2831126b1_9813a61b-bfb9-4090-9e99-a5e9bcbdb007.zip\", \"clobber\": true, \"issue\": 2157853002, \"parent_got_revision\": \"d1a7457666ee116f4500cc7c1e69bff2831126b1\", \"patch_storage\": \"rietveld\", \"patchset\": 1, \"rietveld\": \"https://codereview.chromium.org\"}}", 
    "result": "FAILURE", 
    "result_details_json": "{...}}", 
    "status": "COMPLETED", 
    "status_changed_ts": "1468768218843360", 
    "tags": [
      "builder:win_perf_bisect_builder", 
      "buildset:patch/rietveld/codereview.chromium.org/2157853002/1", 
      "master:tryserver.chromium.perf", 
      "user_agent:recipe"
    ], 
    "updated_ts": "1468768218843680", 
    "url": "http://build.chromium.org/p/tryserver.chromium.perf/builders/win_perf_bisect_builder/builds/13842", 
    "utcnow_ts": "1468768908929700"
  }
}