Demonstrates a bug with Rollup.js when outputing multiple bundles

cd a
npm install
npm link
npm run build

cd ../b
npm install
npm link a
npm run build

b/lib/index.mjs and b/lib/index.bug.mjs should be identical as the only difference between rollup.config.js and rollup.bug.config.js is that the latter outputs multiple bundles.

b/lib/index.bug.mjs references a global external a even though it is imported.

Apparently this occurs only when using class.

rollup 0.34.10

node v6.2.1

npm 3.9.3