TestIndexWriterDelete.testDeleteAllNoDeadlock failure

   [junit4]   2> NOTE: reproduce with: ant test  -Dtestcase=TestIndexWriterDelete -Dtests.method=testDeleteAllNoDeadLock -Dtests.seed=952BE262BA547C1 -Dtests.slow=true -Dtests.badapples=true -Dtests.locale=ar-YE -Dtests.timezone=Europe/Lisbon -Dtests.as\

serts=true -Dtests.file.encoding=US-ASCII

   [junit4] ERROR   0.16s J3 | TestIndexWriterDelete.testDeleteAllNoDeadLock <<<

   [junit4]    > Throwable #1: com.carrotsearch.randomizedtesting.UncaughtExceptionError: Captured an uncaught exception in thread: Thread[id=36, name=Thread-2, state=RUNNABLE, group=TGRP-TestIndexWriterDelete]

   [junit4]    >        at __randomizedtesting.SeedInfo.seed([952BE262BA547C1:3A4B5138AB66FD97]:0)

   [junit4]    > Caused by: java.lang.RuntimeException: java.lang.IllegalArgumentException: field number 0 is already mapped to field name "null", not "content"

   [junit4]    >        at __randomizedtesting.SeedInfo.seed([952BE262BA547C1]:0)

   [junit4]    >        at org.apache.lucene.index.TestIndexWriterDelete$1.run(TestIndexWriterDelete.java:332)

   [junit4]    > Caused by: java.lang.IllegalArgumentException: field number 0 is already mapped to field name "null", not "content"

   [junit4]    >        at org.apache.lucene.index.FieldInfos$FieldNumbers.verifyConsistent(FieldInfos.java:310)

   [junit4]    >        at org.apache.lucene.index.FieldInfos$Builder.getOrAdd(FieldInfos.java:415)

   [junit4]    >        at org.apache.lucene.index.DefaultIndexingChain.getOrAddField(DefaultIndexingChain.java:650)

   [junit4]    >        at org.apache.lucene.index.DefaultIndexingChain.processField(DefaultIndexingChain.java:428)

   [junit4]    >        at org.apache.lucene.index.DefaultIndexingChain.processDocument(DefaultIndexingChain.java:394)

   [junit4]    >        at org.apache.lucene.index.DocumentsWriterPerThread.updateDocuments(DocumentsWriterPerThread.java:297)

   [junit4]    >        at org.apache.lucene.index.DocumentsWriter.updateDocuments(DocumentsWriter.java:450)

   [junit4]    >        at org.apache.lucene.index.IndexWriter.updateDocuments(IndexWriter.java:1291)

   [junit4]    >        at org.apache.lucene.index.IndexWriter.addDocuments(IndexWriter.java:1264)

   [junit4]    >        at org.apache.lucene.index.RandomIndexWriter.addDocument(RandomIndexWriter.java:159)

   [junit4]    >        at org.apache.lucene.index.TestIndexWriterDelete$1.run(TestIndexWriterDelete.java:326)