core: don't use active_machines too much, deletes data

CHANGELOG.md

@@ -6,6 +6,8 @@ BUG FIXES:
     Vagrantfile can cause errors.
   - core: `VAGRANT_VAGRANTFILE` env var only applies to the project
     Vagrantfile name. [GH-2130]
+  - core: Fix an issue where the data directory would be deleted too
+    quickly in a multi-VM environment.
   - provisioners/chef: Work even with restrictive umask on user. [GH-2121]
   - provisioners/chef: Fix environment validation to be less restrictive.
   - provisioners/puppet: No more "shared folders cannot be found" error.

lib/vagrant/plugin/v2/command.rb

@@ -84,6 +84,9 @@ module Vagrant
           names ||= []
           names = [names] if !names.is_a?(Array)
 
+          # Cache the active machines outside the loop
+          active_machines = @env.active_machines
+
           # This is a helper that gets a single machine with the proper
           # provider. The "proper provider" in this case depends on what was
           # given:
@@ -101,7 +104,7 @@ module Vagrant
             provider_to_use = options[:provider]
             provider_to_use = provider_to_use.to_sym if provider_to_use
 
-            @env.active_machines.each do |active_name, active_provider|
+            active_machines.each do |active_name, active_provider|
               if name == active_name
                 # We found an active machine with the same name