00:53:00: INFO: Received results for: ChromeOS-recovery-R59-9460.8.0-sumo.instructions.json
00:53:00: INFO: {
    "status": {
        "status": "failed", 
        "current-time": "Mon, 24 Apr 2017 07:52:30 +0000 (UTC)", 
        "details": "Traceback (most recent call last):\n  File \"//cros/signer/signing_poller.py\", line 944, in SignArtifacts\n    work_dir, insn_cfg, metadata)\n  File \"//cros/signer/signing_poller.py\", line 676, in SignLocalArtifact\n    output_names)\n  File \"//cros/signer/signing_poller.py\", line 522, in SignImage\n    self.signer_if.SignImage(input_image, itype, keyset, output)\n  File \"/cros/signer/image_signer.py\", line 430, in SignImage\n    pre_sign[artifact_type](input_artifact, keyset, output_artifact, **kwargs)\n  File \"/cros/signer/image_signer.py\", line 799, in _PreSignRecovery\n    e.msg, input_artifact)\nImageSigningError: ('Security checks failed: %s. Not signing %s', 'cwd=None', '/tmp/signer.5iDJod/recovery_image.bin')\n", 
        "summary": "('Security checks failed: %s. Not signing %s', 'cwd=None', '/tmp/signer.5iDJod/recovery_image.bin')"
    }, 
    "keyset_is_mp": true, 
    "outputs": {}, 
    "metadata-version": "1", 
    "bot-hostname": "chromeos-signing15.hot.corp.google.com", 
    "keyset": "sumo-mp-v2", 
    "version": {
        "platform": "9460.8.0", 
        "full": "R59-9460.8.0", 
        "milestone": "59"
    }, 
    "board": "sumo", 
    "time": {
        "download": {
            "duration": "0:00:12.208512", 
            "start": "Mon, 24 Apr 2017 07:50:48 +0000 (UTC)"
        }, 
        "start": "Mon, 24 Apr 2017 07:50:45 +0000 (UTC)", 
        "unpack": {
            "duration": "0:01:13.655984", 
            "start": "Mon, 24 Apr 2017 07:51:04 +0000 (UTC)"
        }, 
        "sign": {
            "recovery_image.bin": {
                "duration": "0:00:03.255040", 
                "start": "Mon, 24 Apr 2017 07:52:25 +0000 (UTC)"
            }
        }
    }, 
    "input-archive": "ChromeOS-recovery-R59-9460.8.0-sumo.tar.xz", 
    "type": "recovery", 
    "channel": "canary"
}

Backtrace above in readable form:

Traceback (most recent call last):
  File "//cros/signer/signing_poller.py", line 944, in SignArtifacts
    work_dir, insn_cfg, metadata)
  File "//cros/signer/signing_poller.py", line 676, in SignLocalArtifact
    output_names)
  File "//cros/signer/signing_poller.py", line 522, in SignImage
    self.signer_if.SignImage(input_image, itype, keyset, output)
  File "/cros/signer/image_signer.py", line 430, in SignImage
    pre_sign[artifact_type](input_artifact, keyset, output_artifact, **kwargs)
  File "/cros/signer/image_signer.py", line 799, in _PreSignRecovery
    e.msg, input_artifact)
ImageSigningError: ('Security checks failed: %s. Not signing %s', 'cwd=None', '/tmp/signer.5iDJod/recovery_image.bin')

Adding vapier to cc in case he knows the answer from the top of his head.