See this forum thread: http://ez.no/community/forum/developer/pb_with_ldapusermanage_php_on_ldap_contrib

I wouldn't recommend upgrading to 3.8 if you are using the LDAP login handler and cronjob before this bug gets fixed. Your user tree could behave quite weird (existing locations get removed while they shouldn't, but come back the next time you run the ldap cronjob).