fork + exec = spawn

lib/vagrant-lxc/action/forward_ports.rb

@@ -68,7 +68,7 @@ module Vagrant
           redir_cmd = "sudo redir --laddr=127.0.0.1 --lport=#{host} --cport=#{guest} --caddr=#{@container_ip} 2>/dev/null"
 
           @logger.debug "Forwarding port with `#{redir_cmd}`"
-          fork { exec redir_cmd }
+          spawn redir_cmd
         end
 
         def store_redir_pid(host_port, redir_pid)

spec/unit/action/forward_ports_spec.rb

@@ -22,14 +22,14 @@ describe Vagrant::LXC::Action::ForwardPorts do
     machine.stub(provider: provider, data_dir: data_dir)
 
     subject.stub(exec: true)
-    subject.stub(:fork) { |&block| block.call; pid }
+    subject.stub(spawn: pid)
     subject.call(env)
   end
 
   after { FileUtils.rm_rf data_dir.to_s }
 
   it 'forwards ports using redir' do
-    subject.should have_received(:exec).with(
+    subject.should have_received(:spawn).with(
       "sudo redir --laddr=127.0.0.1 --lport=#{host_port} --cport=#{guest_port} --caddr=#{container_ip} 2>/dev/null"
     )
   end

spec/unit/support/unit_example_group.rb

@@ -14,6 +14,9 @@ module UnitExampleGroup
       Object.any_instance.stub(:fork) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)
       }
+      Object.any_instance.stub(:spawn) { |*args, &block|
+        UnitExampleGroup.prevent_system_calls(*args, &block)
+      }
       require 'vagrant/util/subprocess'
       Vagrant::Util::Subprocess.stub(:execute) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)