Non-parsing Dataset.count() optimization causes inconsistent results for JSON inputs with empty lines

{ "a" : 1 , "b" : 2 , "c" : 3 }

        { "a" : 4 , "b" : 5 , "c" : 6 }
     
{ "a" : 7 , "b" : 8 , "c" : 9 }

scala> val df = spark.read.json("sql/core/src/test/resources/test-data/with-empty-line.json")
df: org.apache.spark.sql.DataFrame = [a: bigint, b: bigint ... 1 more field]

scala> df.count
res0: Long = 3

scala> df.cache.count
res3: Long = 3

scala> val df = spark.read.json("sql/core/src/test/resources/test-data/with-empty-line.json")
df: org.apache.spark.sql.DataFrame = [a: bigint, b: bigint ... 1 more field]

scala> df.count
res0: Long = 7

scala> df.cache.count
res1: Long = 3