In a just fully built jdk forest (e.g. "make images"), a second
invocation of "make images" updates securitypack.jar and does other
work, e.g.

make images
Building target 'images' in configuration '/home/kab/sandboxes/ctbs-friends/fastdebug'
Modifying support/securitypack_jar/jars/securitypack.jar
  updating 1 files
## Starting verify-modules
Checking dependencies across JDK modules
Access verification succeeded.
## Finished verify-modules (build time 00:00:14)

A "make images" for a fully built forest shouldn't find anything it needs to do.