Should we be using logging.warning or warnings.warn?

[MichaelClerx]

See guidance here: https://docs.python.org/3/howto/logging.html#when-to-use-logging

In short

• logging.warning is intended for server-like applications, that lets them emit a warning that the client (typically some other software) can't currently solve (but should be logged somewhere)
• warnings.warn is to notify a user (or client app) of a warning they should try to avoid

My guess is we want the second here?