invalid error message returned when user with expired password authenticates with persistent cookie module

Bug description

Concise statement summarising the error and context (remove this text)

How to reproduce the issue

Create a realm with openam 5.5.1

openam configuration chain 
1.)persistent cook -sufficient 
2.)Ldap-Required

Post authentication class =org.forgerock.openam.authentication.modules.persistentcookie.PersistentCookieAuthModulePostAuthenticationPlugin

Assign a password policy on the ldap identity store that expires passwords

for ex

dsconfig set-password-policy-prop \

          --policy-name Default\ Password\ Policy \

          --set max-password-age:180\ s \

          --set password-expiration-warning-interval:60\ s \

          --hostname opendjconfigstore.example.com \

          --port 4444 \

**         --bindDn cn=Directory\ Manager \

          --bindPasswordFile /home/forgerock/welcome1 \

          --trustAll \

          --no-prompt

Create a subject for the realm in openam

With the users password expired run the following command

curl -v -X POST 'http://openam.example.com:80/openam/json/realms/cookie/authenticate?_=&authIndexType=service&authIndexValue=persistentcookie' -H 'X-OPENAM-USERNAME:cookie' -H 'X-OPENAM-PASSWORD:welcome1'

•   Trying 192.168.1.237...

• TCP_NODELAY set

• Connected to openam551e.example.com (192.168.1.237) port 8080 (#0)

> POST /openam/json/realms/cookie/authenticate?_=&authIndexType=service&authIndexValue=cookie HTTP/1.1

> Host: openam551e.example.com:8080

> User-Agent: curl/7.54.0

> Accept: /

> X-OPENAM-USERNAME:cookie

> X-OPENAM-PASSWORD:welcome1

> Content-Length: 0

> Content-Type: application/x-www-form-urlencoded

>

< HTTP/1.1 500

< X-Frame-Options: SAMEORIGIN

< Set-Cookie: amlbcookie=01; Domain=example.com; Path=/

< Content-API-Version: resource=2.1

< Transfer-Encoding: chunked

< Date: Thu, 10 May 2018 17:35:56 GMT

< Connection: close

< Closing connection 0