Unfortunately I dont remember details off the top of my head though I am certain it was something I tried out.
@omrid
if you NPM LINK your instances to the the global installation then proceed to update the global install, the many instances referencing it will also be updated (because it is a link, not a copy). Alternatively, you could also have a shell script that simply iterates your installations and re-runs the npm link (or full install)
Personally, I don't recommend global installs - even for your use case.
In the mean time, please raise an issue with as much detail and a step by step to reproduce.
Thanks.
