Fix 'start failed' issue (#1262)
Fix 'start failed' issue (#1262)

The start of postgres happens in two stages:
1. First Patroni is waiting for postgres port to be open
2. After that, it is waiting for postgres starts to accept connections

There is a default timeout 60 seconds for both stages (in total).

When the port isn't open, pg_isready exits with code=2.
If postgres is rejecting connections due to recovery, exit code=1.

In most cases postgres quickly opens the port and pg_isready starts returning 1, but in rare cases the whole timeout could spend in `1.`
After that, the HA loop is still waiting for postgres to start, but executing only the check from `2.`. Since pg_isready exit code is still = 2, Patroni was falsely assuming that 'start failed' without taking into consideration the fact that the postmaster process is up and running.

Fixes https://github.com/zalando/patroni/issues/1160
zalando/patroni,zalando/patroni