partman recipe for multiple primary partitions

[seph <seph@directionless.org>]

How can I make a partman-auto recipe that has multiple primary
partitions? I'd like to have a small root, a small swap, and a large
amount of unpartitioned space. I'm trying:

d-i    partman-auto/expert_recipe  string root-swap ::  2048 10000 3072 ext3 $primary{ } method{ format } format{ } use_filesystem{ } filesystem{ ext3 } mountpoint{ / } .  64 512 300% linux-swap $primary{ } method{ swap } format{ } .

but that tells me that there are too many primary partitions. removing
the $primary on the swap partition get's it working. 

Why is it insisting on extended partitions?

seph