TestIndexWriterWithThreads.testOpenTwoIndexWritersOnDifferentThreads test failure [LUCENE-3547]

seen it fail like 5 times while running some tests the last few days (trunk)

```Java
[junit] Testsuite: org.apache.lucene.index.TestIndexWriterWithThreads
[junit] Testcase: testOpenTwoIndexWritersOnDifferentThreads(org.apache.lucene.index.TestIndexWriterWithThreads): FAILED
[junit] Failed due to: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: org.apache.lucene.store.MockLockFactoryWrapper$MockLock@705da7e0
[junit] junit.framework.AssertionFailedError: Failed due to: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: org.apache.lucene.store.MockLockFactoryWrapper$MockLock@705da7e0
[junit] at org.apache.lucene.index.TestIndexWriterWithThreads.testOpenTwoIndexWritersOnDifferentThreads(TestIndexWriterWithThreads.java:447)
[junit] at org.apache.lucene.util.LuceneTestCase$2$1.evaluate(LuceneTestCase.java:615)
[junit] at org.apache.lucene.util.LuceneTestCaseRunner.runChild(LuceneTestCaseRunner.java:149)
[junit] at org.apache.lucene.util.LuceneTestCaseRunner.runChild(LuceneTestCaseRunner.java:51)
[junit]
[junit]
[junit] Tests run: 11, Failures: 1, Errors: 0, Time elapsed: 19.31 sec
[junit]
[junit] ------------- Standard Output ---------------
[junit] org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: org.apache.lucene.store.MockLockFactoryWrapper$MockLock@705da7e0
[junit] at org.apache.lucene.store.Lock.obtain(Lock.java:84)
[junit] at org.apache.lucene.index.IndexWriter.(IndexWriter.java:848)
[junit] at org.apache.lucene.index.TestIndexWriterWithThreads$DelayedIndexAndCloseRunnable.run(TestIndexWriterWithThreads.java:480)
[junit] ------------- ---------------- ---------------
[junit] ------------- Standard Error -----------------
[junit] NOTE: reproduce with: ant test -Dtestcase=TestIndexWriterWithThreads -Dtestmethod=testOpenTwoIndexWritersOnDifferentThreads -Dtests.seed=-75d13bd0fcdda0dd:-554b0eba6bdcc8d:-3f8911a7fc9514ef
[junit] NOTE: test params are: codec=RandomCodecProvider: {field=SimpleText}, sim=RandomSimilarityProvider(queryNorm=false,coord=true): {field=DFR I(F)L2}, locale=ru, timezone=Asia/Pontianak
[junit] NOTE: all tests run in this JVM:
[junit] [TestDateTools, TestByteSlices, TestCompoundFile, TestConsistentFieldNumbers, TestForTooMuchCloning, TestGlobalFieldNumbers, TestIndexCommit, TestIndexWriterWithThreads]
[junit] NOTE: Linux 3.0.6-gentoo amd64/Sun Microsystems Inc. 1.6.0_27 (64-bit)/cpus=8,threads=1,free=112228008,total=240975872
[junit] ------------- ---------------- ---------------
```

---
Migrated from [LUCENE-3547](https://issues.apache.org/jira/browse/LUCENE-3547) by selckin

Start with TestIndexWriterWithThreads.java, especially testOpenTwoIndexWritersOnDifferentThreads around line 447 and DelayedIndexAndCloseRunnable around line 480. Run the provided Ant command with the recorded seed, then investigate the lock-timeout failure; done means the test no longer fails intermittently when opening writers on different threads.

Written by the indexing model from the issue text.