Updated everything, got this odd message:

[Doug Simon]

> On 19 Jan 2017, at 12:40, Andrew Haley <aph at redhat.com> wrote:
> 
> On 18/01/17 20:45, Doug Simon wrote:
>> I may be missing some trick for incrementally compiling a replacement JDK module so any hints in that direction would be appreciated ;-)
> 
> I guess we should take this to the Jigsaw list.  Graal won't be the
> only module with problems of this kind.

Well, I suspect the answer will be that with jdk9 javac, one simply has to compile everything in a module at once. This is not how the Graal module is built since it is decomposed into smaller mx projects compiled separately and is finally assembled into a module.

-Doug