DISTINCT statement over UNION ALL subquery asserts during execution with streaming aggregation

0: jdbc:drill:schema=dfs> select distinct sq.x1, sq.x2, sq.x3 from ( select a1, b1, c1 from t1 union all select a2, b2, c2 from t2 ) as sq(x1,x2,x3);
+------------+------------+------------+
|     x1     |     x2     |     x3     |
+------------+------------+------------+
Query failed: RemoteRpcException: Failure while running fragment., Failure while reading vector.  Expected vector class of org.apache.drill.exec.vector.NullableVarCharVector but was holding vector class org.apache.drill.exec.vector.NullableIntVector. [ dd2fedd7-bbee-40a4-8a26-9ca86fa774f6 on atsqa4-134.qa.lab:31010 ]
[ dd2fedd7-bbee-40a4-8a26-9ca86fa774f6 on atsqa4-134.qa.lab:31010 ]


java.lang.RuntimeException: java.sql.SQLException: Failure while executing query.
        at sqlline.SqlLine$IncrementalRows.hasNext(SqlLine.java:2514)
        at sqlline.SqlLine$TableOutputFormat.print(SqlLine.java:2148)
        at sqlline.SqlLine.print(SqlLine.java:1809)
        at sqlline.SqlLine$Commands.execute(SqlLine.java:3766)
        at sqlline.SqlLine$Commands.sql(SqlLine.java:3663)
        at sqlline.SqlLine.dispatch(SqlLine.java:889)
        at sqlline.SqlLine.begin(SqlLine.java:763)
        at sqlline.SqlLine.start(SqlLine.java:498)
        at sqlline.SqlLine.main(SqlLine.java:460)

00-01      Project(x1=[$0], x2=[$1], x3=[$2])
00-02        StreamAgg(group=[{0, 1, 2}])
00-03          Sort(sort0=[$0], sort1=[$1], sort2=[$2], dir0=[ASC], dir1=[ASC], dir2=[ASC])
00-04            Project(x1=[$0], x2=[$1], x3=[$2])
00-05              UnionAll(all=[true])
00-07                Project(a1=[$2], b1=[$1], c1=[$0])
00-09                  Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/aggregation/sanity/t1]], selectionRoot=/aggregation/sanity/t1, numFiles=1, columns=[`a1`, `b1`, `c1`]]])
00-06                Project(a2=[$1], b2=[$0], c2=[$2])
00-08                  Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/aggregation/sanity/t2]], selectionRoot=/aggregation/sanity/t2, numFiles=1, columns=[`a2`, `b2`, `c2`]]])

0: jdbc:drill:schema=dfs> select distinct sq.x1, sq.x2, sq.x3 from ( select a1, b1, c1 from t1 union all select a1, b1, c1 from t4 ) as sq(x1,x2,x3);
+------------+------------+------------+
|     x1     |     x2     |     x3     |
+------------+------------+------------+
| 1          | aaaaa      | 2015-01-01 |
| 2          | bbbbb      | 2015-01-02 |
| 3          | ccccc      | 2015-01-03 |
| 4          | null       | 2015-01-04 |
| 5          | eeeee      | 2015-01-05 |
| 6          | fffff      | 2015-01-06 |
| 7          | ggggg      | 2015-01-07 |
| 9          | iiiii      | null       |
| 10         | jjjjj      | 2015-01-10 |
| null       | hhhhh      | 2015-01-08 |
+------------+------------+------------+
10 rows selected (0.131 seconds)

2015-02-10 23:10:10,387 [2b25702c-e73f-3af8-810b-cf7555854ab5:frag:0:0] WARN  o.a.d.e.e.ExpressionTreeMaterializer - Unable to find value vector of path `a1`, returning null instance.
2015-02-10 23:10:10,387 [2b25702c-e73f-3af8-810b-cf7555854ab5:frag:0:0] WARN  o.a.d.e.e.ExpressionTreeMaterializer - Unable to find value vector of path `b1`, returning null instance.
2015-02-10 23:10:10,387 [2b25702c-e73f-3af8-810b-cf7555854ab5:frag:0:0] WARN  o.a.d.e.e.ExpressionTreeMaterializer - Unable to find value vector of path `c1`, returning null instance.
2015-02-10 23:10:10,389 [2b25702c-e73f-3af8-810b-cf7555854ab5:frag:0:0] WARN  o.a.d.e.w.fragment.FragmentExecutor - Error while initializing or executing fragment
java.lang.IllegalStateException: Failure while reading vector.  Expected vector class of org.apache.drill.exec.vector.NullableVarCharVector but was holding vector class org.apache.drill.exec.vector.NullableIntVector.
        at org.apache.drill.exec.record.VectorContainer.getValueAccessorById(VectorContainer.java:239) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.getValueAccessorById(AbstractRecordBatch.java:191) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.validate.IteratorValidatorBatchIterator.getValueAccessorById(IteratorValidatorBatchIterator.java:110) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.test.generated.SingleBatchSorterGen6510.doSetup(SingleBatchSorterTemplate.java:211) ~[na:na]
        at org.apache.drill.exec.test.generated.SingleBatchSorterGen6510.setup(SingleBatchSorterTemplate.java:42) ~[na:na]
        at org.apache.drill.exec.physical.impl.xsort.ExternalSortBatch.innerNext(ExternalSortBatch.java:315) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:142) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.validate.IteratorValidatorBatchIterator.next(IteratorValidatorBatchIterator.java:118) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:99) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:89) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.aggregate.StreamingAggBatch.innerNext(StreamingAggBatch.java:105) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:142) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.validate.IteratorValidatorBatchIterator.next(IteratorValidatorBatchIterator.java:118) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:99) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:89) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractSingleRecordBatch.innerNext(AbstractSingleRecordBatch.java:51) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.project.ProjectRecordBatch.innerNext(ProjectRecordBatch.java:134) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.record.AbstractRecordBatch.next(AbstractRecordBatch.java:142) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.validate.IteratorValidatorBatchIterator.next(IteratorValidatorBatchIterator.java:118) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.BaseRootExec.next(BaseRootExec.java:67) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.ScreenCreator$ScreenRoot.innerNext(ScreenCreator.java:97) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.physical.impl.BaseRootExec.next(BaseRootExec.java:57) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.work.fragment.FragmentExecutor.run(FragmentExecutor.java:116) ~[drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at org.apache.drill.exec.work.WorkManager$RunnableWrapper.run(WorkManager.java:303) [drill-java-exec-0.8.0-SNAPSHOT-rebuffed.jar:0.8.0-SNAPSHOT]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_71]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_71]
        at java.lang.Thread.run(Thread.java:745) [na:1.7.0_71]
2015-02-10 23:10:10,390 [2b25702c-e73f-3af8-810b-cf7555854ab5:frag:0:0] ERROR o.a.drill.exec.ops.FragmentContext - Fragment Context received failure.