SERVER-40926 createIndexes should return IndexBuildAlreadyInProgress errors

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• Closed

SERVER-39323 Don't consider in-progress indexes when deciding whether or not to build an index under an intent lock

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• Closed

SERVER-40990 If a createIndexes request specifies two identical indexes, a IndexAlreadyExists error is thrown and no index is ever created

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• Closed

SERVER-37644 Make the createIndexes command join already in-progress index builds

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• Closed