npm ls not listing duplicate webpack

[penx]

I'm opening this issue because:

• npm is crashing.
• npm is producing an incorrect install.
• npm is doing something I don't understand.
• Other (see below for feature requests):

What's going wrong?

npm ls webpack is not correctly showing all installations of webpack, when 4 is installed as a package dependency and 3 is installed as a sub dependency.

I think this a bug with npm ls.

How can the CLI team reproduce the problem?

Start a new package as follows:

npm init -y
npm install @storybook/react@3.3.14 --save-dev
npm ls webpack

You should see the following output:

example-project@1.0.0
└─┬ @storybook/react@3.3.14
  └── webpack@3.11.0

This is correct, as @storybook/react has the following in dependencies:

"webpack": "^3.10.0", 

Then install a version of webpack that differs from the @storybook/react dependency:

npm install webpack@4 --save-dev
npm ls webpack

I would expect to get:

example-project@1.0.0
├─┬ @storybook/react@3.3.14
│ └─ webpack@3.11.0
└── webpack@4.0.1

But actually get:

example-project@1.0.0
└── webpack@4.0.1

However, example-project/node_modules/@storybook/react/node_modules/webpack does exist on disk, so the module is there but is missing from npm ls.

supporting information:

• npm -v prints: 5.6.0
• node -v prints: v8.9.3
• npm config get registry prints: https://registry.npmjs.org/
• Windows, OS X/macOS, or Linux?: OS X
• Network issues:
  • Geographic location where npm was run:
  • I use a proxy to connect to the npm registry.
  • I use a proxy to connect to the web.
  • I use a proxy when downloading Git repos.
  • I access the npm registry via a VPN
  • I don't use a proxy, but have limited or unreliable internet access.
• Container:
  • I develop using Vagrant on Windows.
  • I develop using Vagrant on OS X or Linux.
  • I develop / deploy using Docker.
  • I deploy to a PaaS (Triton, Heroku).