ldap: fixed regression in extracting settings after library updates.

- somehow we now got '' defaulted to None which changed the behaviour.

rhodecode/authentication/base.py

@@ -218,7 +218,10 b' class RhodeCodeAuthPluginBase(object):'
         else:
             plugin_settings = SettingsModel().get_all_settings()
 
-        return plugin_settings.get(full_name) or default
+        if full_name in plugin_settings:
+            return plugin_settings[full_name]
+        else:
+            return default
 
     def create_or_update_setting(self, name, value):
         """

rhodecode/authentication/plugins/auth_ldap.py

@@ -195,7 +195,7 b' class AuthLdap(object):'
     def __init__(self, server, base_dn, port=389, bind_dn='', bind_pass='',
                  tls_kind='PLAIN', tls_reqcert='DEMAND', ldap_version=3,
                  search_scope='SUBTREE', attr_login='uid',
-                 ldap_filter=None):
+                 ldap_filter=''):
         if ldap == Missing:
             raise LdapImportError("Missing or incompatible ldap library")