Rollup can't find node_modules when run via gobble

[martypdx]

May be a rollup issue, but thought I'd start here.

Best I can tell the isExternal function doesn't work correctly and plugins never get called. I noticed options.external and tried some stuff out, but over my head figuring out how that iteracts with calling plugins.

Output looks like:

input:  /Users/marty/rollup-rxjs/.gobble-build/01-include/1
output: /Users/marty/rollup-rxjs/.gobble-build/02-rollup/1
>>>
Cannot find module 'rxjs/Observable' from '/Users/marty/rollup-rxjs/.gobble-build/01-include/1'
Error: Cannot find module 'rxjs/Observable' from '/Users/marty/rollup-rxjs/.gobble-build/01-include/1'

Here's branch with simple example project I'm hacking on to try this.