Building a second index on a FAT32 drive from OSX fails with OverlappingFileLockException [LUCENE-3481]

Building a new index using FSDirectory.open(new File(path) on a FAT32 drive from OSX. Once the index has built but the index writer has not been closed because I want to optimize it I create a new indexwriter to create a second completely different index. However this fails with

Exception in thread "main" java.nio.channels.OverlappingFileLockException
at sun.nio.ch.FileChannelImpl$SharedFileLockTable.checkList(FileChannelImpl.java:1166)
at sun.nio.ch.FileChannelImpl$SharedFileLockTable.add(FileChannelImpl.java:1068)
at sun.nio.ch.FileChannelImpl.tryLock(FileChannelImpl.java:868)
at java.nio.channels.FileChannel.tryLock(FileChannel.java:962)
at org.apache.lucene.store.NativeFSLock.obtain(NativeFSLockFactory.java:216)
at org.apache.lucene.store.Lock.obtain(Lock.java:72)
at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:1097)

but this should not occur as I am not locking the same file, this second index is being built in a different directory albeit with the same parent directory as the other index.

I think the issue is specifically to do with OSX - FAT32 interaction because the problem always occurs, but never occurs if I build the indexes on the internal Mac drive.

The only way I could resolve this was to remove locking using

FSDirectory.open(new File(path), NoLockFactory.getNoLockFactory() );

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Migrated from [LUCENE-3481](https://issues.apache.org/jira/browse/LUCENE-3481) by Paul taylor
Environment:
```
Mac OSX 10.7 Lion with attached FAT32 disc
```

Start by reproducing the failure with FSDirectory.open(new File(path)) on Mac OS X 10.7 using an attached FAT32 drive, while creating two indexes in separate directories sharing a parent. Read the NativeFSLock.obtain and IndexWriter stack frames first; done means the second IndexWriter can be created without OverlappingFileLockException while the indexes remain separate.

Written by the indexing model from the issue text.