'knife ec2 server create' DISCONNECT with proxy

I’m spinning up new ec2 instances with this:

knife ec2 server create --flavor t1.micro --image ami-a8ddf7ed --region
us-west-1 --availability-zone us-west-1b --run-list
’role[location_hub],role[role_admin]’ --ephemeral /dev/sdb --node-name
test23.hub.foobar.com --security-group-id sg-61ba8a24 -user-data
/tmp/cloud-init.yml -c /home/doug/.chef/hub/knife.rb -w bcadmin@ -x

The host where this is run is in Amazon region us-west-2. The proxy host is in
region us-west-1. The new box is in region us-west-1. The command typically,
but not always fails with:

Waiting for sshd.done
Bootstrapping Chef on ec2-50-18-238-32.us-west-1.compute.amazonaws.com
ERROR: Net::SSH::Disconnect: connection closed by remote host

I ran tcpdump on the proxy host and confirmed that the ssh traffic never gets
past the proxy. It seems like if I add debug with -VV, it works every time.
This seems to heavily indicate a timing issue/bug with knife or ruby’s ssh

Chef client version (on the new nodes) is 11.6.0-1.ubuntu.12.04. On the box
running knife ec2, it’s 11.6.0-1.ubuntu.12.04. The knife ec2 plugin version is