python3-cephfs focal 'syntax warning' is/literal

[Harry Coin]

During apt install from an otherwise blank focal/mate:

setting up python3-cephfs (15.2.1-0ubuntu2) ...
/usr/lib/python3/dist-packages/ceph_volume_client.py:358: SyntaxWarning: "is not" with a literal. Did you mean "!="?
  group_id = group_id if group_id is not 'None' else None
/usr/lib/python3/dist-packages/ceph_volume_client.py:381: SyntaxWarning: "is" with a literal. Did you mean "=="?
  readonly = True if access_level is 'r' else False
/usr/lib/python3/dist-packages/ceph_volume_client.py:1102: SyntaxWarning: "is" with a literal. Did you mean "=="?

...
The compiler now produces a SyntaxWarning when identity checks (is and is not) are used with certain types of literals (e.g. strings, numbers). These can often work by accident in CPython, but are not guaranteed by the language spec. The warning advises users to use equality tests (== and !=) instead. (Contributed by Serhiy Storchaka in bpo-34850.)

[Harry Coin (hcoin)]

Good detail here on why this can go horribly wrong if ignored:
https://adamj.eu/tech/2020/01/21/why-does-python-3-8-syntaxwarning-for-is-literal/

[Kai Kasurinen (kai-kasurinen)]

https://github.com/ceph/ceph/pull/34637
https://github.com/ceph/ceph/pull/34974

[Rolf Leggewie (r0lf)]

fixed upstream in v15.2.9 (https://docs.ceph.com/en/latest/releases/octopus/#v15-2-9-octopus), so focal-security and later are no longer affected