[SPARK-5725] [SQL] Fixes ParquetRelation2.equals

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Author: Cheng Lian <lian@databricks.com>

Closes #4513 from liancheng/spark-5725 and squashes the following commits:

bf6a087 [Cheng Lian] Fixes ParquetRelation2.equals

sql/core/src/main/scala/org/apache/spark/sql/parquet/newParquet.scala

@@ -152,6 +152,7 @@ case class ParquetRelation2
       paths.toSet == relation.paths.toSet &&
         maybeMetastoreSchema == relation.maybeMetastoreSchema &&
         (shouldMergeSchemas == relation.shouldMergeSchemas || schema == relation.schema)
+    case _ => false
   }
 
   private[sql] def sparkContext = sqlContext.sparkContext