javac crashes (and does not reject) a module declaration with a package statement

$ cat play/src/x/module-info.java
package p;

module x { }
jjg@jjg-Precision-T7600:/w/jjg/work/jigsaw/jake$ ./build/linux-x86_64-normal-server-release/jdk/bin/javac play/src/x/module-info.java
An exception has occurred in the compiler (9-internal). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
at com.sun.tools.javac.comp.TypeEnter$ImportsPhase.checkClassPackageClash(jdk.compiler/TypeEnter.java:377)
at com.sun.tools.javac.comp.TypeEnter$ImportsPhase.resolveImports(jdk.compiler/TypeEnter.java:348)
at com.sun.tools.javac.comp.TypeEnter$ImportsPhase.access$1700(jdk.compiler/TypeEnter.java:290)
at com.sun.tools.javac.comp.TypeEnter.lambda$ensureImportsChecked$0(jdk.compiler/TypeEnter.java:167)
at com.sun.tools.javac.comp.TypeEnter.finishImports(jdk.compiler/TypeEnter.java:218)
at com.sun.tools.javac.comp.TypeEnter.ensureImportsChecked(jdk.compiler/TypeEnter.java:167)
at com.sun.tools.javac.comp.Enter.complete(jdk.compiler/Enter.java:557)
at com.sun.tools.javac.comp.Enter.main(jdk.compiler/Enter.java:528)
at com.sun.tools.javac.main.JavaCompiler.enterTrees(jdk.compiler/JavaCompiler.java:1038)
at com.sun.tools.javac.main.JavaCompiler.compile(jdk.compiler/JavaCompiler.java:904)
at com.sun.tools.javac.main.Main.compile(jdk.compiler/Main.java:281)
at com.sun.tools.javac.main.Main.compile(jdk.compiler/Main.java:144)
at com.sun.tools.javac.Main.compile(jdk.compiler/Main.java:55)
at com.sun.tools.javac.Main.main(jdk.compiler/Main.java:41)