A couple of random BF failures in kerberosCheck

Hello,

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=elver&dt=2019-07-24%2003%3A22%3A17
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=crake&dt=2019-08-02%2007%3A17%3A25

I wondered if this might be like the recently fixed problem with slapd
not being ready to handle requests yet, since we start up krb5kdc
first and then don't do anything explicit to wait for it, but it
doesn't look like an obvious failure to reach it.  It looks like test
3 on elver connected successfully but didn't like the answer it got
for this query:

SELECT gss_authenticated AND encrypted from pg_stat_gssapi where pid =
pg_backend_pid();

-- 
Thomas Munro
https://enterprisedb.com