do not treat the empty string as a valid classpath component

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@5657 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/compiler/scala/tools/ant/ScalaTool.scala

@@ -136,7 +136,7 @@ package scala.tools.ant {
       * @param input The value of <code>classpath</code>. */
     def setClasspath(input: String) =
       classpath = classpath :::
-	(List.fromArray(input.split(":")).map(p => "#PREFIX#/" + p))
+	(List.fromArray(input.split(":")).filter(p => p != "").map(p => "#PREFIX#/" + p))
     
     /** Sets the properties attribute. Used by Ant.
       * @param input The value for <code>properties</code>. */