auth_pam libraries missing from RHEL6 packages?

We recently upgraded our test server from 5.5 to 5.6, but all the PAM auth libraries appear to have disappeared, which has locked out the users we had converted to pam_auth.

[root@sands ~]# rpm -qa | grep Percona
Percona-Server-shared-56-5.6.15-rel63.0.519.rhel6.x86_64
Percona-Server-client-56-5.6.15-rel63.0.519.rhel6.x86_64
Percona-Server-server-56-5.6.15-rel63.0.519.rhel6.x86_64
[root@sands ~]# rpm -ql Percona-Server-server-56-5.6.15-rel63.0.519.rhel6.x86_64 | grep pam
[root@sands ~]#

Here’s the difference on one of servers that’s still 5.5:
[root@frontier ~]# rpm -qa | grep Percona
Percona-Server-shared-55-5.5.30-rel30.2.508.rhel6.x86_64
Percona-Server-server-55-5.5.30-rel30.2.508.rhel6.x86_64
Percona-Server-client-55-5.5.30-rel30.2.508.rhel6.x86_64
[root@frontier ~]# rpm -ql Percona-Server-server-55 | grep pam
/usr/lib64/mysql/plugin/auth_pam.so
/usr/lib64/mysql/plugin/auth_pam_compat.so
/usr/lib64/mysql/plugin/debug/auth_pam.so
/usr/lib64/mysql/plugin/debug/auth_pam_compat.so
[root@frontier ~]# rpm -qf /usr/lib64/mysql/plugin/auth_pam*
Percona-Server-server-55-5.5.30-rel30.2.508.rhel6.x86_64
Percona-Server-server-55-5.5.30-rel30.2.508.rhel6.x86_64

Where have the libraries gone? We’ve reviewed http://www.percona.com/doc/percona-server/5.6/changed_in_56.html#changed-in-56 and it claims that these are on the list of features that were ported from 5.5 to 5.6 and not related to anything that was removed.