pg_ident mapping Kerberos Usernames

Hi,

I'm trying to get pg_ident to map "user1" and "user1(at)A(dot)DOMAIN(dot)TLD" to
"user1" in postgres, or vice versa. I'm not picky about which way works.

Kerberos authentication works. I've gotten "user1" to login successfully
with a Kerberos ticket, but I'm not able to get "user1(at)A(dot)DOMAIN(dot)TLD" to
match.

Environment:
* PostgreSQL 9.6 from PostgreSQL repos
* CentOS 7
* FreeIPA for Kerberos, LDAP, etc.
* Realm A.DOMAIN.TLD
* "user1" database exists
* "user1" role exists
* Logging into CentOS usernames are configured to drop the domain, so
they appear as "user1" rather then "user1(at)a(dot)domain(dot)tld".

pg_hba.conf:

local all postgres peer
host all all 127.0.0.1/32 md5
host all all ::1/128 md5
host all all 192.168.1.0/24 gss
include_realm=1 map=testnet krb_realm=A.DOMAIN.TLD #This is on one line.
Thunderbird is truncating lines.

pg_ident.conf:

testnet /^([0-9A-Za-z_-]+)@A\.DOMAIN\.TLD$ \1
testnet /^([0-9A-Za-z_-]+)$ \1

Regex that works for both in regexr.com:

/^([0-9A-Za-z-_]+)(@A\.DOMAIN\.TLD)?$/gm

Command and lines from pg_log:

$ psql -h db0 # Logged in as user1 with Kerberos ticket

< 2017-09-09 19:50:49.376 CDT - 192.168.1.201 [unknown] > LOG:
connection received: host=192.168.1.201 port=44918
< 2017-09-09 19:50:49.398 CDT - 192.168.1.201 user1 > LOG: connection
authorized: user=user1 database=user1
< 2017-09-09 19:50:50.912 CDT - 192.168.1.201 user1 > LOG:
disconnection: session time: 0:00:01.537 user=user1 database=user1
host=192.168.1.201 port=44918

$ psql -h db0 -U user1(at)A(dot)DOMAIN(dot)TLD # Logged in as user1 with Kerberos
ticket

< 2017-09-09 19:50:54.959 CDT - 192.168.1.201 [unknown] > LOG:
connection received: host=192.168.1.201 port=44920
< 2017-09-09 19:50:55.023 CDT - 192.168.1.201 user1(at)A(dot)DOMAIN(dot)TLD > LOG:
no match in usermap "testnet" for user "user1(at)A(dot)DOMAIN(dot)TLD"
authenticated as "user1(at)A(dot)DOMAIN(dot)TLD"
< 2017-09-09 19:50:55.023 CDT - 192.168.1.201 user1(at)A(dot)DOMAIN(dot)TLD >
FATAL: GSSAPI authentication failed for user "user1(at)A(dot)DOMAIN(dot)TLD"
< 2017-09-09 19:50:55.023 CDT - 192.168.1.201 user1(at)A(dot)DOMAIN(dot)TLD >
DETAIL: Connection matched pg_hba.conf line 87: "host all
all 192.168.1.0/24 gss include_realm=1
map=testnet krb_realm=A.DOMAIN.TLD"

Is this something that is possible, or is it something where I need to
pick one way to do it?

Thanks in advance,
Ryan