javac throw NPE when -cp includes "/"

 ~/bin/jdk1.9.0b90/bin/javac -cp "/" Test.java

java.lang.NullPointerException
at com.sun.tools.javac.file.JavacFileManager.listContainer(JavacFileManager.java:401)
at com.sun.tools.javac.file.JavacFileManager.list(JavacFileManager.java:678)
at com.sun.tools.javac.code.ClassFinder.scanUserPaths(ClassFinder.java:566)
at com.sun.tools.javac.code.ClassFinder.fillIn(ClassFinder.java:513)
at com.sun.tools.javac.code.ClassFinder.complete(ClassFinder.java:295)
at com.sun.tools.javac.code.ClassFinder.access$000(ClassFinder.java:74)
at com.sun.tools.javac.code.ClassFinder$1.complete(ClassFinder.java:166)
at com.sun.tools.javac.code.Symbol.complete(Symbol.java:579)
at com.sun.tools.javac.comp.Enter.visitTopLevel(Enter.java:299)
at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:509)
at com.sun.tools.javac.comp.Enter.classEnter(Enter.java:255)
at com.sun.tools.javac.comp.Enter.classEnter(Enter.java:270)
at com.sun.tools.javac.comp.Enter.complete(Enter.java:483)
at com.sun.tools.javac.comp.Enter.main(Enter.java:467)
at com.sun.tools.javac.main.JavaCompiler.enterTrees(JavaCompiler.java:962)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:839)
at com.sun.tools.javac.main.Main.compile(Main.java:254)
at com.sun.tools.javac.main.Main.compile(Main.java:142)
at com.sun.tools.javac.Main.compile(Main.java:56)
at com.sun.tools.javac.Main.main(Main.java:42)