Fix --die-on-broken-pipe not propagated properly

At the end of parsing options, we add an empty string to child
arguments. This caused the arguments to py4j.JavaGateway to be
interpreted as ["", "--die-on-broken-pipe", "0"].

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -128,7 +128,7 @@ object SparkSubmit {
       }
       if (args.primaryResource == PYSPARK_SHELL) {
         args.mainClass = "py4j.GatewayServer"
-        args.childArgs ++= ArrayBuffer("--die-on-broken-pipe", "0")
+        args.childArgs = ArrayBuffer("--die-on-broken-pipe", "0")
       } else {
         // If a python file is provided, add it to the child arguments and list of files to deploy.
         // Usage: PythonAppRunner <main python file> <extra python files> [app arguments]

core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala

@@ -302,7 +302,9 @@ private[spark] class SparkSubmitArguments(args: Seq[String]) {
               parse(tail)
           }
         } else {
-          childArgs += value
+          if (!value.isEmpty) {
+            childArgs += value
+          }
           parse(tail)
         }