[CX] After failed rebalance, Index resource couldn't be found, The number of active operations cannot be negative!

After rebalance failure described in MB-26269, a subsequent drop dataset on the dataset which failed to rebalance, the following exceptions are observed:

2017-10-04T09:06:25.053-07:00 WARN CBAS.nc.Task [Executor-7:4825f8dc0a41996f563b6844fd2f5549] Task TAID:TID:ANID:ODID:0:0:0:0 failed with exception org.apache.hyracks.api.exceptions.HyracksDataException: Index resource couldn't be found. Has it been created yet? Was it deleted? at org.apache.hyracks.storage.am.common.dataflow.IndexDataflowHelper.readIndex(IndexDataflowHelper.java:75) ~[hyracks-storage-am-common-0.3.3-SNAPSHOT.jar:0.3.3-SNAPSHOT] at org.apache.hyracks.storage.am.common.dataflow.IndexDataflowHelper.destroy(IndexDataflowHelper.java:98) ~[hyracks-storage-am-common-0.3.3-SNAPSHOT.jar:0.3.3-SNAPSHOT] at org.apache.hyracks.storage.am.common.dataflow.IndexDropOperatorNodePushable.initialize(IndexDropOperatorNodePushable.java:56) ~[hyracks-storage-am-common-0.3.3-SNAPSHOT.jar:0.3.3-SNAPSHOT]

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org.apache.hyracks.api.exceptions.HyracksDataException: The number of active operations cannot be negative! at org.apache.asterix.common.context.PrimaryIndexOperationTracker.completeOperation(PrimaryIndexOperationTracker.java:85) ~[asterix-common-0.9.3-SNAPSHOT.jar:0.9.3-SNAPSHOT] at org.apache.asterix.metadata.MetadataNode.deleteTupleFromIndex(MetadataNode.java:835) ~[asterix-metadata-0.9.3-SNAPSHOT.jar:0.9.3-SNAPSHOT] at org.apache.asterix.metadata.MetadataNode.dropNodegroup(MetadataNode.java:734) ~[asterix-metadata-0.9.3-SNAPSHOT.jar:0.9.3-SNAPSHOT]