local/global temp view should not accept duplicate column names

scala> spark.sql("create temp view v1 as select 1 as col1, 2 as col1")
res0: org.apache.spark.sql.DataFrame = []

scala> spark.sql("select col1 from v1").show
19/07/04 22:27:19 WARN ObjectStore: Failed to get database global_temp, returning NoSuchObjectException
org.apache.spark.sql.AnalysisException: Reference 'col1' is ambiguous, could be: v1.col1, v1.col1.; line 1 pos 7
  at org.apache.spark.sql.catalyst.expressions.package$AttributeSeq.resolve(package.scala:259)
  at org.apache.spark.sql.catalyst.plans.logical.LogicalPlan.resolveChildren(LogicalPlan.scala:101)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveReferences$$anonfun$40.apply(Analyzer.scala:890)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveReferences$$anonfun$40.apply(Analyzer.scala:892)
  at org.apache.spark.sql.catalyst.analysis.package$.withPosition(package.scala:53)