toPandas with no partitions should work

>>> spark.sparkContext.emptyRDD().toDF("col1 int").toPandas()
  An error occurred while calling o158.getResult.
: org.apache.spark.SparkException: Exception thrown in awaitResult:
	at org.apache.spark.util.ThreadUtils$.awaitResult(ThreadUtils.scala:226)
	at org.apache.spark.api.python.PythonServer.getResult(PythonRDD.scala:874)
	at org.apache.spark.api.python.PythonServer.getResult(PythonRDD.scala:870)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
	at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
	at py4j.Gateway.invoke(Gateway.java:282)
	at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
	at py4j.commands.CallCommand.execute(CallCommand.java:79)
	at py4j.GatewayConnection.run(GatewayConnection.java:238)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NegativeArraySizeException
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1$$anonfun$apply$17.apply(Dataset.scala:3293)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1$$anonfun$apply$17.apply(Dataset.scala:3287)
	at org.apache.spark.sql.Dataset$$anonfun$52.apply(Dataset.scala:3370)
	at org.apache.spark.sql.execution.SQLExecution$$anonfun$withNewExecutionId$1.apply(SQLExecution.scala:80)
	at org.apache.spark.sql.execution.SQLExecution$.withSQLConfPropagated(SQLExecution.scala:127)
	at org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:75)
	at org.apache.spark.sql.Dataset.org$apache$spark$sql$Dataset$$withAction(Dataset.scala:3369)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1.apply(Dataset.scala:3287)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1.apply(Dataset.scala:3286)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply$mcV$sp(PythonRDD.scala:456)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply(PythonRDD.scala:456)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply(PythonRDD.scala:456)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7.apply(PythonRDD.scala:457)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7.apply(PythonRDD.scala:453)
	at org.apache.spark.api.python.SocketFuncServer.handleConnection(PythonRDD.scala:994)
	at org.apache.spark.api.python.SocketFuncServer.handleConnection(PythonRDD.scala:988)
	at org.apache.spark.api.python.PythonServer$$anonfun$11$$anonfun$apply$9.apply(PythonRDD.scala:853)
	at scala.util.Try$.apply(Try.scala:192)
	at org.apache.spark.api.python.PythonServer$$anonfun$11.apply(PythonRDD.scala:853)
	at org.apache.spark.api.python.PythonServer$$anonfun$11.apply(PythonRDD.scala:852)
	at org.apache.spark.api.python.PythonServer$$anon$1.run(PythonRDD.scala:908)

  warnings.warn(msg)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/hyukjin.kwon/workspace/forked/spark/python/pyspark/sql/dataframe.py", line 2132, in toPandas
    batches = self.toDF(*tmp_column_names)._collectAsArrow()
  File "/Users/hyukjin.kwon/workspace/forked/spark/python/pyspark/sql/dataframe.py", line 2223, in _collectAsArrow
    jsocket_auth_server.getResult()  # Join serving thread and raise any exceptions
  File "/Users/hyukjin.kwon/workspace/forked/spark/python/lib/py4j-0.10.7-src.zip/py4j/java_gateway.py", line 1257, in __call__
  File "/Users/hyukjin.kwon/workspace/forked/spark/python/pyspark/sql/utils.py", line 63, in deco
    return f(*a, **kw)
  File "/Users/hyukjin.kwon/workspace/forked/spark/python/lib/py4j-0.10.7-src.zip/py4j/protocol.py", line 328, in get_return_value
py4j.protocol.Py4JJavaError: An error occurred while calling o158.getResult.
: org.apache.spark.SparkException: Exception thrown in awaitResult:
	at org.apache.spark.util.ThreadUtils$.awaitResult(ThreadUtils.scala:226)
	at org.apache.spark.api.python.PythonServer.getResult(PythonRDD.scala:874)
	at org.apache.spark.api.python.PythonServer.getResult(PythonRDD.scala:870)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
	at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
	at py4j.Gateway.invoke(Gateway.java:282)
	at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
	at py4j.commands.CallCommand.execute(CallCommand.java:79)
	at py4j.GatewayConnection.run(GatewayConnection.java:238)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NegativeArraySizeException
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1$$anonfun$apply$17.apply(Dataset.scala:3293)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1$$anonfun$apply$17.apply(Dataset.scala:3287)
	at org.apache.spark.sql.Dataset$$anonfun$52.apply(Dataset.scala:3370)
	at org.apache.spark.sql.execution.SQLExecution$$anonfun$withNewExecutionId$1.apply(SQLExecution.scala:80)
	at org.apache.spark.sql.execution.SQLExecution$.withSQLConfPropagated(SQLExecution.scala:127)
	at org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:75)
	at org.apache.spark.sql.Dataset.org$apache$spark$sql$Dataset$$withAction(Dataset.scala:3369)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1.apply(Dataset.scala:3287)
	at org.apache.spark.sql.Dataset$$anonfun$collectAsArrowToPython$1.apply(Dataset.scala:3286)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply$mcV$sp(PythonRDD.scala:456)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply(PythonRDD.scala:456)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7$$anonfun$apply$3.apply(PythonRDD.scala:456)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7.apply(PythonRDD.scala:457)
	at org.apache.spark.api.python.PythonRDD$$anonfun$7.apply(PythonRDD.scala:453)
	at org.apache.spark.api.python.SocketFuncServer.handleConnection(PythonRDD.scala:994)
	at org.apache.spark.api.python.SocketFuncServer.handleConnection(PythonRDD.scala:988)
	at org.apache.spark.api.python.PythonServer$$anonfun$11$$anonfun$apply$9.apply(PythonRDD.scala:853)
	at scala.util.Try$.apply(Try.scala:192)
	at org.apache.spark.api.python.PythonServer$$anonfun$11.apply(PythonRDD.scala:853)
	at org.apache.spark.api.python.PythonServer$$anonfun$11.apply(PythonRDD.scala:852)
	at org.apache.spark.api.python.PythonServer$$anon$1.run(PythonRDD.scala:908)