IndexWriter.Init may orphan its write lock in case of exception

In IndexWriter.Init, if an exception other than IOException is thrown after the write lock has been acquired, the lock is not released. (See Index\IndexWriter.cs:1922 for a starting point.)

Specifically, the exception we have seen occuring is UnauthorizedAccessException, eg "Access to the path 'C:\foo\bar\segments.gen' is denied".

Stack trace from the UnauthorizedAccessException as mentioned above:
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
at Lucene.Net.Store.SimpleFSDirectory.SimpleFSIndexInput.Descriptor..ctor(FileInfo file, FileAccess mode)
at Lucene.Net.Store.SimpleFSDirectory.OpenInput(String name, Int32 bufferSize)
at Lucene.Net.Store.FSDirectory.OpenInput(String name)
at Lucene.Net.Index.SegmentInfos.FindSegmentsFile.Run(IndexCommit commit)
at Lucene.Net.Index.SegmentInfos.Read(Directory directory)
at Lucene.Net.Index.IndexWriter.Init(Directory d, Analyzer a, Boolean create, Boolean closeDir, IndexDeletionPolicy deletionPolicy, Boolean autoCommit, Int32 maxFieldLength, IndexingChain indexingChain, IndexCommit commit)
at Lucene.Net.Index.IndexWriter..ctor(Directory d, Analyzer a, Boolean create, MaxFieldLength mfl)

I do not know under what circumstances that initial exception occurred but after this has happened all subsequent attempts at accessing the index will fail.

It seems that changing the catch statement to release the writelock regardless of exception type should solve this