Viewing Setup File Diff throws DirectoryNotFoundException

[mrward]

Steps To Reproduce

1. Build SharpDevelop from source
2. Rename one of the addin folders (e.g. AddinManager2 to AddinManager-new-2)
3. Select View - Setup - Files
4. Right click Program Files folder and select Diff.

Expected result

Missing AddinManager2 directory is handled and diff produced.

Actual result

--> Exception:
System.IO.DirectoryNotFoundException: Could not find a part of the path 'd:\projects\sharpdevelop\addins\misc\addinmanager2'.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileSystemEnumerableIterator`1.CommonInit()
   at System.IO.FileSystemEnumerableIterator`1..ctor(String path, String originalUserPath, String searchPattern, SearchOption searchOption, SearchResultHandler`1 resultHandler, Boolean checkHost)
   at System.IO.Directory.GetDirectories(String path)
   at ICSharpCode.WixBinding.DirectoryReader.GetDirectories(String path) in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\DirectoryReader.cs:line 21
   at ICSharpCode.WixBinding.WixPackageFilesDiff.GetNewDirectories() in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\WixPackageFilesDiff.cs:line 170
   at ICSharpCode.WixBinding.WixPackageFilesDiff.Compare(WixDirectoryElementBase directoryElement) in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\WixPackageFilesDiff.cs:line 97
   at ICSharpCode.WixBinding.WixPackageFilesEditor.CalculateDiff() in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\WixPackageFilesEditor.cs:line 234
   at ICSharpCode.WixBinding.WixPackageFilesControl.CalculateDiff() in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\Gui\WixPackageFilesControl.cs:line 286
   at ICSharpCode.WixBinding.PackageFilesView.CalculateDiff() in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\Gui\PackageFilesView.cs:line 154
   at ICSharpCode.WixBinding.ShowDiffCommand.Run(PackageFilesView view) in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\Commands\ShowDiffCommand.cs:line 22
   at ICSharpCode.WixBinding.AbstractActivePackageFilesViewCommand.Run() in SharpDevelop\src\AddIns\BackendBindings\WixBinding\Project\Src\Commands\AbstractActivePackageFilesViewCommand.cs:line 32
   at ICSharpCode.Core.AbstractMenuCommand.System.Windows.Input.ICommand.Execute(Object parameter) in SharpDevelop\src\Main\Core\Project\Src\Util\AbstractCommand.cs:line 60
   at ICSharpCode.SharpDevelop.Workbench.WpfWorkbench.ExecuteCommand(ICommand command, Object caller) in SharpDevelop\src\Main\SharpDevelop\Workbench\WpfWorkbench.cs:line 155
   at ICSharpCode.Core.WinForms.MenuCommand.OnClick(EventArgs e) in SharpDevelop\src\Main\ICSharpCode.Core.WinForms\Menu\MenuCommand.cs:line 71