TestStressIndexing2.testMultiConfig() failure: all instances of a given field name must have the same term vectors settings [LUCENE-6941]

ASF Jenkins found this failure: . I was able to reproduce by beasting (1/10 dups failed on the first beast iteration):

```
[junit4] Suite: org.apache.lucene.index.TestStressIndexing2
[junit4] 2> NOTE: download the large Jenkins line-docs file by running 'ant get-jenkins-line-docs' in the lucene directory.
[junit4] 2> NOTE: reproduce with: ant test -Dtestcase=TestStressIndexing2 -Dtests.method=testMultiConfig -Dtests.seed=337C1E3DCE453481 -Dtests.multiplier=2 -Dtests.nightly=true -Dtests.slow=true -Dtests.linedocsfile=/x1/jenkins/lucene-data/enwiki.random.lines.txt -Dtests.locale=hr_HR -Dtests.timezone=Asia/Shanghai -Dtests.asserts=true -Dtests.file.encoding=UTF-8
[junit4] ERROR 1.92s J1 | TestStressIndexing2.testMultiConfig <<<
[junit4] > Throwable #1: java.lang.IllegalArgumentException: all instances of a given field name must have the same term vectors settings (storeTermVectorOffsets changed for field="f0")
[junit4] > at __randomizedtesting.SeedInfo.seed([337C1E3DCE453481:FEEE68E563132BCF]:0)
[junit4] > at org.apache.lucene.index.TermVectorsConsumerPerField.start(TermVectorsConsumerPerField.java:170)
[junit4] > at org.apache.lucene.index.TermsHashPerField.start(TermsHashPerField.java:292)
[junit4] > at org.apache.lucene.index.FreqProxTermsWriterPerField.start(FreqProxTermsWriterPerField.java:74)
[junit4] > at org.apache.lucene.index.DefaultIndexingChain$PerField.invert(DefaultIndexingChain.java:611)
[junit4] > at org.apache.lucene.index.DefaultIndexingChain.processField(DefaultIndexingChain.java:344)
[junit4] > at org.apache.lucene.index.DefaultIndexingChain.processDocument(DefaultIndexingChain.java:300)
[junit4] > at org.apache.lucene.index.DocumentsWriterPerThread.updateDocument(DocumentsWriterPerThread.java:234)
[junit4] > at org.apache.lucene.index.DocumentsWriter.updateDocument(DocumentsWriter.java:450)
[junit4] > at org.apache.lucene.index.IndexWriter.updateDocument(IndexWriter.java:1477)
[junit4] > at org.apache.lucene.index.IndexWriter.addDocument(IndexWriter.java:1256)
[junit4] > at org.apache.lucene.index.TestStressIndexing2.indexSerial(TestStressIndexing2.java:250)
[junit4] > at org.apache.lucene.index.TestStressIndexing2.testMultiConfig(TestStressIndexing2.java:106)
[junit4] > at java.lang.Thread.run(Thread.java:745)
[junit4] > Suppressed: java.lang.IllegalStateException: close() called in wrong state: RESET
[junit4] > at org.apache.lucene.analysis.MockTokenizer.fail(MockTokenizer.java:126)
[junit4] > at org.apache.lucene.analysis.MockTokenizer.close(MockTokenizer.java:293)
[junit4] > at org.apache.lucene.analysis.TokenFilter.close(TokenFilter.java:58)
[junit4] > at org.apache.lucene.index.DefaultIndexingChain$PerField.invert(DefaultIndexingChain.java:687)
[junit4] > ... 44 more
[junit4] 2> NOTE: leaving temporary files on disk at: /x1/jenkins/jenkins-slave/workspace/Lucene-Solr-NightlyTests-5.x/lucene/build/core/test/J1/temp/lucene.index.TestStressIndexing2_337C1E3DCE453481-001
[junit4] 2> NOTE: test params are: codec=Asserting(Lucene54): {f25=FSTOrd50, f32=FSTOrd50, id=PostingsFormat(name=LuceneVarGapDocFreqInterval), f19=Lucene50(blocksize=128), f68=Lucene50(blocksize=128), f43=FSTOrd50, f15=Lucene50(blocksize=128), f14=FSTOrd50, f95=Lucene50(blocksize=128), f33=Lucene50(blocksize=128), f65=FSTOrd50, f93=Lucene50(blocksize=128), f77=Lucene50(blocksize=128), f12=PostingsFormat(name=LuceneVarGapDocFreqInterval), f71=Lucene50(blocksize=128), f83=FSTOrd50, f91=Lucene50(blocksize=128), f2=Lucene50(blocksize=128), f40=Lucene50(blocksize=128), f10=FSTOrd50, f28=Lucene50(blocksize=128), f92=PostingsFormat(name=LuceneVarGapDocFreqInterval), f81=PostingsFormat(name=LuceneVarGapDocFreqInterval), f57=Lucene50(blocksize=128), f22=Lucene50(blocksize=128), f58=FSTOrd50, f23=PostingsFormat(name=LuceneVarGapDocFreqInterval), f13=Lucene50(blocksize=128), f46=Lucene50(blocksize=128), f48=Lucene50(blocksize=128), f82=Lucene50(blocksize=128), f36=FSTOrd50, f52=PostingsFormat(name=LuceneVarGapDocFreqInterval), f31=Lucene50(blocksize=128), f27=PostingsFormat(name=LuceneVarGapDocFreqInterval), f90=FSTOrd50, f69=FSTOrd50, f80=Lucene50(blocksize=128), f73=Lucene50(blocksize=128), f17=Lucene50(blocksize=128), f1=PostingsFormat(name=LuceneVarGapDocFreqInterval), f86=Lucene50(blocksize=128), f63=PostingsFormat(name=LuceneVarGapDocFreqInterval), f26=Lucene50(blocksize=128), f64=Lucene50(blocksize=128), f51=Lucene50(blocksize=128), f84=Lucene50(blocksize=128), f5=PostingsFormat(name=LuceneVarGapDocFreqInterval), f8=Lucene50(blocksize=128), f49=PostingsFormat(name=LuceneVarGapDocFreqInterval), f20=Lucene50(blocksize=128), f29=FSTOrd50, f59=Lucene50(blocksize=128), f39=Lucene50(blocksize=128), f9=PostingsFormat(name=LuceneVarGapDocFreqInterval), f55=Lucene50(blocksize=128), f94=FSTOrd50, f99=Lucene50(blocksize=128), f74=PostingsFormat(name=LuceneVarGapDocFreqInterval), f47=FSTOrd50, f41=PostingsFormat(name=LuceneVarGapDocFreqInterval), f37=Lucene50(blocksize=128), f98=FSTOrd50, f21=FSTOrd50, f42=Lucene50(blocksize=128), f62=Lucene50(blocksize=128), f89=PostingsFormat(name=LuceneVarGapDocFreqInterval), f7=FSTOrd50, f67=PostingsFormat(name=LuceneVarGapDocFreqInterval), f78=PostingsFormat(name=LuceneVarGapDocFreqInterval), f24=Lucene50(blocksize=128), f56=PostingsFormat(name=LuceneVarGapDocFreqInterval), f76=FSTOrd50, f0=Lucene50(blocksize=128), f38=PostingsFormat(name=LuceneVarGapDocFreqInterval), f53=Lucene50(blocksize=128), f16=PostingsFormat(name=LuceneVarGapDocFreqInterval), f72=FSTOrd50, f54=FSTOrd50, f45=PostingsFormat(name=LuceneVarGapDocFreqInterval)}, docValues:{}, sim=DefaultSimilarity, locale=hr_HR, timezone=Asia/Shanghai
[junit4] 2> NOTE: Linux 3.13.0-52-generic amd64/Oracle Corporation 1.7.0_80 (64-bit)/cpus=4,threads=1,free=199000432,total=376963072
[junit4] 2> NOTE: All tests run in this JVM: [TestNRTCachingDirectory, TestCodecs, TestIntArrayDocIdSet, TestPayloads, TestFastDecompressionMode, TestScoreCachingWrappingScorer, TestDateTools, TestIntBlockPool, TestIndexWriterForceMerge, TestUnicodeUtil, TestIndexWriterDeleteByQuery, TestBinaryDocument, TestCachingTokenFilter, TestLongBitSet, TestAddIndexes, TestDisjunctionMaxQuery, TestLucene50TermVectorsFormat, TestMergeSchedulerExternal, Test2BNumericDocValues, TestMultiCollector, TestIndexWriterMaxDocs, TestDirectoryReaderReopen, TestFieldReuse, TestDocument, TestSpanExplanationsOfNonMatches, TestSameScoresWithThreads, TestOmitPositions, TestBytesRefArray, TestDuelingCodecsAtNight, TestTermVectors, TestWeakIdentityMap, TestTermdocPerf, TestSegmentMerger, TestNIOFSDirectory, TestNewestSegment, TestNeedsScores, TestNotDocIdSet, TestDemoParallelLeafReader, TestBooleanMinShouldMatch, TestPositiveScoresOnlyCollector, TestFieldMaskingSpanQuery, TestSpanSearchEquivalence, TestFieldValueQuery, TestFilteredSearch, TestFieldType, TestForceMergeForever, TestFixedBitDocIdSet, TestStressIndexing2]
[junit4] Completed [91/414 (1!)] on J1 in 2.28s, 3 tests, 1 error <<< FAILURES!
```

---
Migrated from [LUCENE-6941](https://issues.apache.org/jira/browse/LUCENE-6941) by Steven Rowe (@sarowe)

Start with lucene/core/src/test/org/apache/lucene/index/TestStressIndexing2.java, especially testMultiConfig() and indexSerial(), then reproduce using the listed ant command and seed. Trace the failure from TermVectorsConsumerPerField.start() through DefaultIndexingChain. Done means the reported TestStressIndexing2.testMultiConfig failure is understood and the test passes reliably under the reproducing configuration.

Written by the indexing model from the issue text.