Openstack overcoud scale out fails with: derive_pci_passthrough_whitelist.py ... ValueError: No JSON object could be decoded

Issue

The Ansible failed task shows:

TASK [run derive_pci_passthrough_whitelist.py] *********************************
    fatal: [localhost]: FAILED! => {"changed": true, "cmd": ["/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py"], "delta": "0:00:00.571837", "end": "2023-04-06 10:11:41.118246", "msg": "non-zero return code", "rc": 1, "start": "2023-04-06 10:11:40.546409", "stderr": "Traceback (most recent call last):\n  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 308, in <module>\n    user_configs = user_passthrough_config()\n  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 149, in user_passthrough_config\n    return json.loads(out)\n  File \"/usr/lib64/python2.7/json/__init__.py\", line 338, in loads\n    return _default_decoder.decode(s)\n  File \"/usr/lib64/python2.7/json/decoder.py\", line 366, in decode\n    obj, end = self.raw_decode(s, idx=_w(s, 0).end())\n  File \"/usr/lib64/python2.7/json/decoder.py\", line 384, in raw_decode\n    raise ValueError(\"No JSON object could be decoded\")\nValueError: No JSON object could be decoded", "stderr_lines": ["Traceback (most recent call last):", "  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 308, in <module>", "    user_configs = user_passthrough_config()", "  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 149, in user_passthrough_config", "    return json.loads(out)", "  File \"/usr/lib64/python2.7/json/__init__.py\", line 338, in loads", "    return _default_decoder.decode(s)", "  File \"/usr/lib64/python2.7/json/decoder.py\", line 366, in decode", "    obj, end = self.raw_decode(s, idx=_w(s, 0).end())", "  File \"/usr/lib64/python2.7/json/decoder.py\", line 384, in raw_decode", "    raise ValueError(\"No JSON object could be decoded\")", "ValueError: No JSON object could be decoded"], "stdout": "", "stdout_lines": []}

If you prettify the json:

{
  "changed": true,
  "cmd": [
    "/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py"
  ],
  "delta": "0:00:00.571837",
  "end": "2023-04-06 10:11:41.118246",
  "msg": "non-zero return code",
  "rc": 1,
  "start": "2023-04-06 10:11:40.546409",
  "stderr": "Traceback (most recent call last):\n  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 308, in <module>\n    user_configs = user_passthrough_config()\n  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 149, in user_passthrough_config\n    return json.loads(out)\n  File \"/usr/lib64/python2.7/json/__init__.py\", line 338, in loads\n    return _default_decoder.decode(s)\n  File \"/usr/lib64/python2.7/json/decoder.py\", line 366, in decode\n    obj, end = self.raw_decode(s, idx=_w(s, 0).end())\n  File \"/usr/lib64/python2.7/json/decoder.py\", line 384, in raw_decode\n    raise ValueError(\"No JSON object could be decoded\")\nValueError: No JSON object could be decoded",
  "stderr_lines": [
    "Traceback (most recent call last):",
    "  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 308, in <module>",
    "    user_configs = user_passthrough_config()",
    "  File \"/var/lib/pci_passthrough_whitelist_scripts/derive_pci_passthrough_whitelist.py\", line 149, in user_passthrough_config",
    "    return json.loads(out)",
    "  File \"/usr/lib64/python2.7/json/__init__.py\", line 338, in loads",
    "    return _default_decoder.decode(s)",
    "  File \"/usr/lib64/python2.7/json/decoder.py\", line 366, in decode",
    "    obj, end = self.raw_decode(s, idx=_w(s, 0).end())",
    "  File \"/usr/lib64/python2.7/json/decoder.py\", line 384, in raw_decode",
    "    raise ValueError(\"No JSON object could be decoded\")",
    "ValueError: No JSON object could be decoded"
  ],
  "stdout": "",
  "stdout_lines": []
}