Chefvm and KNIFE_CHEF_SERVER

In my .basrc I have this: export KNIFE_CHEF_SERVER=http://33.33.33.1:8889,
which is a local chef-zero server

in my .chefvm/configurations/chef-east/knife.rb I have this:
chef_server_url “https://chef-east.foo.in”, which our production chef
server

Vagrant seems to rely on KNIFE_CHEF_SERVER from the environment here:
chef.chef_server_url = ENV[‘KNIFE_CHEF_SERVER’]

So when I run 'chefvm use ’ it sets up the chef_server_url
from the .chefvm/configurations/chef-east/knife.rb correctly but the
env var: KNIFE_CHEF_SERVER, stays the same

Am I doing something wrong here? I would have thought vagrant would have
used the chef_server_url setting in the
.chefvm/configurations/chef-east/knife.rb.

Right now when I run chefvm use <some_server>, I have to manually change
the KNIFE_CHEF_SERVER env var.