Fix Vagrantfile to handle multiple env variables.

Environment variables are now passed as a list,
instead of a string.

.travis.yml

@@ -58,7 +58,8 @@ matrix:
       language: python
       python: 3.5
     # Not a Salt node, runs test suite instead
-    - env: SALT_NODE_ID=test
+    - env:
+        - SALT_NODE_ID=test
       os: linux
       sudo: required
       dist: trusty

Vagrantfile

@@ -1,7 +1,7 @@
 require 'yaml'
 
 def extract_id(env)
-  id = env.split.map do |env_var|
+  id = env.map do |env_var|
     env_var[/^SALT_NODE_ID=(?<node_id>.+)$/, "node_id"]
   end.compact
   id[0]
@@ -37,7 +37,7 @@ Vagrant.configure(2) do |config|
     elsif node_config[:id] != 'test'
       node_config
     end
-  end.compact.each do |node|
+  end.compact.uniq.each do |node|
     config.vm.define node[:id] do |machine|
       machine.vm.box = node[:box]
       machine.vm.provider :virtualbox do |vbox|