If no shared folders existed, don't worry about clearing them

lib/vagrant/actions/vm/shared_folders.rb

@@ -31,6 +31,7 @@ module Vagrant
         end
 
         def clear_shared_folders
+          if runner.vm.shared_folders.length > 0
             logger.info "Clearing previously set shared folders..."
 
             folders = @runner.vm.shared_folders.dup
@@ -40,6 +41,7 @@ module Vagrant
 
             @runner.reload!
           end
+        end
 
         def create_metadata
           logger.info "Creating shared folders metadata..."

test/vagrant/actions/vm/shared_folders_test.rb

@@ -81,6 +81,12 @@ class SharedFoldersActionTest < Test::Unit::TestCase
       @runner.expects(:reload!).once.in_sequence(destroy_seq)
       @action.clear_shared_folders
     end
+
+    should "do nothing if no shared folders existed" do
+      @shared_folders.clear
+      @runner.expects(:reload!).never
+      @action.clear_shared_folders
+    end
   end
 
   context "setting up shared folder metadata" do