[BUG] npm 7.5.x is deleting all packages when one package is updated (global)

[JoeUX]

Current Behavior:

All my global packages are being deleted when I run an npm update -g ... command, except for the package that I'm updating. This has been happening for at least a month. Currently it's happening with npm 7.5.4, but I think it was also happening with earlier 7.5.x releases. See the screenshot below.

Expected Behavior:

It should just update the specified package. It should not delete any packages.

Steps To Reproduce:

1. Start with Node 14.15.5 (LTS) on Windows 10 Pro 64-bit.
2. Install the latest npm globally with npm install -g npm@latest. Currently this installs npm 7.5.4.
3. Install a bunch of packages globally with npm install -g ....
4. Wait a few days for updates to some packages to become available. Check with npm -g outdated.
5. Update a package, e.g. npm update -g eslint.
6. List your installed packages with npm ls -g --depth=0.
7. They're all gone except for the one you just updated (in this case eslint).
8. Check C:\Users\Joe\AppData\Roaming\npm\node_modules. All module folders are gone, except for the package you just updated.
9. Check npm version with npm -g -v. It says npm 6.14.10, probably the version that shipped with Node 14.15.5. npm deleted itself too, at least the updated version.

Screenshot captures everything:

Environment:

• OS: Windows 10 Pro 64-bit 20H2
• Node: 14.15.5
• npm: 7.5.4

[ljharb]

to update a global eslint, you'd run npm install -g eslint - there's no global lockfile, so npm update doesn't do anything for you there.

that said, there shouldn't ever be any auto-pruning on npm root -g, and this does seem like a bug.

[greg-hornby-roam]

This happened to me on version 8.1