Is LDAP login case-sensitive in Red Hat Enterprise Linux 6 ?

Issue

• There is a difference in how logins through LDAP are handled between Red Hat Enterprise Linux (RHEL) 4 and RHEL5 on the one hand and RHEL6 on the other.  In RHEL6 the logins are case sensitive, in previous versions they were case insensitive.

RHEL6: case sensitive.

    # id User
    uid=40549(User) gid=40550(User) groups=40550(User)
    # id user 
    id: user: No such user

RHEL4: case-insensitive.

    # id User
    uid=40549(User) gid=40550(User) groups=40550(User)    
    # id user
    uid=40549(user) gid=40550(user) groups=40550(user)

• Is there a way to enable RHEL6 to handle case insensitive login names?
• Is the ldap.conf configuration item nss_check_case recognized and supported in RHEL6?