Sssd refuses to change user's password when ldap_pwd_policy is set to shadow
and LDAP server has disabled password policies support.

Changing ldap_pwd_policy to none in sssd.conf fixes the problem.
Enabling ppolicy module and configuring ppolicy overlay in slapd also fixes the problem.

Conditions:

- sssd.conf settings:

id_provider                     = ldap
access_provider                 = ldap
auth_provider                   = ldap
chpass_provider                 = ldap
ldap_pwd_policy                 = shadow

- user has shadowAccount attributes,
- slapd has ppolicy module disabled,
- slapd has ppolicy overlay disabled.

I'm attaching debug logs of slapd, sssd and PAM messages
obtained during the password change operation:

http://pastebin.com/KE9UVZKh