Do AD check if AD is enabled.

lib/gitlab/ldap/group.rb

@@ -38,9 +38,11 @@ module Gitlab
         elsif member_dns.include?(user.dn)
           true
         else
+          if Gitlab.config.ldap.active_directory
             adapter.dn_matches_filter?(user.dn, active_directory_recursive_memberof_filter)
           end
         end
+      end
 
       def member_dns
         if entry.respond_to? :member