javac: error: Cannot resolve module dependencies using Jigsaw module resolver

[Alan Bateman]

Jon - I've been using the updated javac and it works very well except 
for the diagnostics. When attempting to compile a module and a 
dependency that cannot be resolved then the output isn't very 
informative. I find that I need to set JIGSAW_TRACE to reveal the 
problem. I realize this is an issue with jmod install too, but I thought 
I should point it out as an area that probably needs works.

-Alan.