Don't use forward slash in exclusion for JAR signature files

project/SparkBuild.scala

@@ -236,7 +236,7 @@ object SparkBuild extends Build {
   def extraAssemblySettings() = Seq(test in assembly := {}) ++ Seq(
     mergeStrategy in assembly := {
       case m if m.toLowerCase.endsWith("manifest.mf") => MergeStrategy.discard
-      case m if m.toLowerCase.matches("meta-inf/.*\\.sf$") => MergeStrategy.discard
+      case m if m.toLowerCase.matches("meta-inf.*\\.sf$") => MergeStrategy.discard
       case "reference.conf" => MergeStrategy.concat
       case _ => MergeStrategy.first
     }