Webrev: http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8173096/webrev.00/index.html
A recent change in jmod tool [1] creates the JMOD file with no group and other readable permission as that’s the default permission when creating a temporary file with Files::createTempFile. This fixes the permission issue by creating the JMOD file in a temporary directory. Mandy [1] https://bugs.openjdk.java.net/browse/JDK-8173096
