core: add option to not lock for Machine#action [GH-4574]

CHANGELOG.md

@@ -88,6 +88,8 @@ BUG FIXES:
 
 PLUGIN AUTHOR CHANGES:
 
+  - `Machine#action` can be called with the option `lock: false` to not
+      acquire a machine lock.
   - `Machine#reload` will now properly trigger the `machine_id_changed`
       callback on providers.
 

lib/vagrant/machine.rb

@@ -144,9 +144,12 @@ module Vagrant
     # @param [Hash] extra_env This data will be passed into the action runner
     #   as extra data set on the environment hash for the middleware
     #   runner.
-    def action(name, extra_env=nil)
+    def action(name, extra_env=nil, **opts)
       @logger.info("Calling action: #{name} on provider #{@provider}")
 
+      # Default to locking
+      opts[:lock] = true if !opts.has_key?(:lock)
+
       # Create a deterministic ID for this machine
       vf = nil
       vf = @env.vagrantfile_name[0] if @env.vagrantfile_name
@@ -157,7 +160,7 @@ module Vagrant
       # we will want to do more fine-grained unlocking in actions themselves
       # but for a 1.6.2 release this will work.
       locker = Proc.new { |*args, &block| block.call }
-      locker = @env.method(:lock) if !name.to_s.start_with?("ssh")
+      locker = @env.method(:lock) if opts[:lock] && !name.to_s.start_with?("ssh")
 
       # Lock this machine for the duration of this action
       locker.call("machine-action-#{id}") do