nfsv3 exports return no auth flavors in ubuntu 9.04

[km]

Binary package hint: nfs-kernel-server

Starting in 9.04 an nfsv3 export with no "sec=" parameter in /etc/exports, responds to a mount rcp with "no flavors".
Previous versions returned a default list.

The man page says

The sec= option, followed by a colon-delimited list of security
              flavors, restricts the export to clients using those flavors.
              Available security flavors include sys (the default-

I find contrary to this documentation, I need to add sec=sys to the exports entry to get the "default" behavior.

This null flavor list doesn't seem to effect Linux clients, but Solaris clients need a list. So after a 8.10->9.04 upgrade, all my Solaris client mounts broke until I modified the Linux exports file.