CBO (Calcite Return Path): Insert overwrite... select * from... queries failing for bucketed tables

set hive.enforce.bucketing = true;
set hive.enforce.sorting = true;
set hive.exec.reducers.max = 1;

CREATE TABLE tbl1(key int, value string) CLUSTERED BY (key) SORTED BY (key) INTO 2 BUCKETS;

insert overwrite table tbl1
select * from src where key < 10;

java.lang.Exception: java.lang.RuntimeException: Error in configuring object
        at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
        at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:529)
Caused by: java.lang.RuntimeException: Error in configuring object
        at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:109)
        at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:75)
        at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:133)
        at org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:409)
        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:392)
        at org.apache.hadoop.mapred.LocalJobRunner$Job$ReduceTaskRunnable.run(LocalJobRunner.java:319)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:106)
        ... 10 more
Caused by: java.lang.RuntimeException: Reduce operator initialization failed
        at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.configure(ExecReducer.java:157)
        ... 14 more
Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.RuntimeException: cannot find field key from [0:_col0, 1:_col1]
        at org.apache.hadoop.hive.ql.exec.FileSinkOperator.initializeOp(FileSinkOperator.java:446)
        at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:362)
        at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:481)
        at org.apache.hadoop.hive.ql.exec.Operator.initializeChildren(Operator.java:438)
        at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:375)
        at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:481)
        at org.apache.hadoop.hive.ql.exec.Operator.initializeChildren(Operator.java:438)
        at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:375)
        at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.configure(ExecReducer.java:150)
        ... 14 more
Caused by: java.lang.RuntimeException: cannot find field key from [0:_col0, 1:_col1]
        at org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.getStandardStructFieldRef(ObjectInspectorUtils.java:416)
        at org.apache.hadoop.hive.serde2.objectinspector.StandardStructObjectInspector.getStructFieldRef(StandardStructObjectInspector.java:147)
        at org.apache.hadoop.hive.ql.exec.ExprNodeColumnEvaluator.initialize(ExprNodeColumnEvaluator.java:55)
        at org.apache.hadoop.hive.ql.exec.Operator.initEvaluators(Operator.java:978)
        at org.apache.hadoop.hive.ql.exec.FileSinkOperator.initializeOp(FileSinkOperator.java:383)
        ... 22 more