Fix handling of invalid sockets returned by PQsocket()

When Who What
2016-03-09 02:21:24 Peter Eisentraut (petere) Closed in commitfest 2016-03 with status: Committed
2016-03-09 02:21:24 Peter Eisentraut (petere) Changed committer to petere
2016-03-03 01:51:08 Peter Eisentraut (petere) Added petere as reviewer
2016-02-17 05:28:00 Michael Paquier (michael-kun) Attached mail thread CAB7nPqRo22qwYVegew3MX8nF-NHUnQywU_fZi7Vkp2HV91eXCw@mail.gmail.com
2016-02-16 06:42:07 Michael Paquier (michael-kun) Changed authors to Michael Paquier (michael-kun)
2016-02-16 06:41:57 Michael Paquier (michael-kun) Attached mail thread 20160212212502.GA590606@alvherre.pgsql
2016-02-16 06:41:57 Michael Paquier (michael-kun) Created patch record