list-dids-extended with new metadata plugin currently fails

[bari12]

Motivation

rucio set-metadata --did
CTA_LAPP_FREDERIC:cta_data_DL0_ObsId2021_02_22_15_49_11_975413919_TelId0.h
df5 --key ObsID --value 1

rucio get-metadata
CTA_LAPP_FREDERIC:cta_data_DL0_ObsId2021_02_22_15_49_11_975413919_TelId0.h
df5 --plugin ALL
bsID:           1
access_cnt:      None
accessed_at:     None
....

rucio list-dids-extended --filter ObsID=1 CTA_LAPP_FREDERIC:*
/usr/lib/python2.7/site-packages/paramiko/transport.py:33:
CryptographyDeprecationWarning: Python 2 is no longer supported by the
Python core team. Support for it is now deprecated in cryptography, and
will be removed in a future release.
  from cryptography.hazmat.backends import default_backend
2021-02-22 15:58:35,693 ERROR   An unknown exception occurred.
Details: no error information passed (http status code: 500
('internal_server_error', 'server_error', '/o\\', '\xe2\x9c\x97'))