Postgres instrumentation is incomplete

[stas]

The instrumentation is not covering the psycopg2 extensions API.
In order to reproduce this, try calling psycopg2.extensions.ISQLQuote.prepare() with the wrapped connection object, it will raise a

 TypeError
must be psycopg2._psycopg.connection, not PGConnectionProxy

An example of such an use-case is when trying to adapt an iterator in an array column type query.
To be specific, peewee is using such an adapter:
https://github.com/coleifer/peewee/blob/master/playhouse/postgres_ext.py#L109-L117

[roncohen]

Hey @stas! Thanks for this. I'll take a look.