Improve two phase transaction requirement detection for PG
Improved detection of two phase transactions requirement for the PostgreSQL
database by testing that max_prepared_transactions is set to a value
greater than 0. Pull request courtesy Federico Caselli.
Fixes: #5057
Closes: #5059
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5059
Pull-request-sha:
c30c3b1a5216d281db84f9fa48466edaf7a26d1e
Change-Id: I4360f62eacdf1173172ee24cd05a68e9a448290c
(cherry picked from commit
92fd25f3e1f69b6fbdc3b2bbd81508a01a2668b3)