#### Issue description When declaring a node version 8.X.X, snapcraft builds fail with a variety of errors. #### Steps to reproduce the issue 1. Explicitly point 'node-engine' to 8.10.0 2. run 'snapcraft' ``` name: hello-node-snap version: "1.0.2" summary: A simple hello world command description: hello world confinement: strict apps: hello-node-snap: command: bin/hello-node-snap plugs: [network] parts: hello-node-snap: plugin: nodejs node-engine: 8.10.0 node-packages: - hello-node-snap ``` #### What's the expected result? I've received the following errors: [Errno 2] No such file or directory: mysnapdirectory/prime/bin/hello-node-snap OSError: [Errno 26] Text file busy: mysnapdirectory/parts/hello-node-snap/install/bin/node #### Additional details It looks as if npm is creating a package.json lockfile and silently failing.