Search new sync candidate amoung potential and async standbys (#794)
Search new sync candidate amoung potential and async standbys (#794)

In synchronos_mode_strict we put '*' into synchronos_standby_names, what makes one connection 'sync' and other connections 'potential'.
The code picking up the correct sync standby didn't consider 'potential' as a good candidate.

Fixes: https://github.com/zalando/patroni/issues/789
zalando/patroni,zalando/patroni