CleanMachineFolder won't run if the folder is < 10 characters. Small safeguard againt unwanted rm-rfs.

lib/vagrant/action/vm/clean_machine_folder.rb

@@ -19,6 +19,12 @@ module Vagrant
 
         def clean_machine_folder
           folder = File.join(VirtualBox::Global.global.system_properties.default_machine_folder, "*")
+
+          # Small safeguard against potentially unwanted rm-rf, since the default
+          # machine folder will typically always be greater than 10 characters long.
+          # For users with it < 10, out of luck?
+          return if folder.length < 10
+
           Dir[folder].each do |f|
             next unless File.directory?(f)
 

test/vagrant/action/vm/clean_machine_folder_test.rb

@@ -19,7 +19,7 @@ class CleanMachineFolderVMActionTest < Test::Unit::TestCase
 
   context "cleaning the folder" do
     setup do
-      @machine_folder = "foo"
+      @machine_folder = "/foo/bar/baz"
       @folder = File.join(@machine_folder, "*")
       VirtualBox::Global.global.system_properties.stubs(:default_machine_folder).returns(@machine_folder)
       File.stubs(:file?).returns(true)
@@ -73,5 +73,10 @@ class CleanMachineFolderVMActionTest < Test::Unit::TestCase
 
       @instance.clean_machine_folder
     end
+
+    should "do nothing if folder is < 10 characters" do
+      VirtualBox::Global.global.system_properties.stubs(:default_machine_folder).returns("foo")
+      Dir.expects(:[]).never
+    end
   end
 end