[BUG] installing git dep on non-existent branch results in unhelpful error message

[ericprud]

### Current Behavior:

Expected Behavior:

npm install with erroneous git version on a github dependency whines about cache "already exists"

Steps To Reproduce:

1. with a fresh npm package.json, add a dep for a non-existent branch, e.g."dependencies": { "shex-test": "github:shexSpec/shexTest#master" }
2. npm install --cache /tmp/brand-new-cache

Environment:

• OS: Ubuntu 20.04

Error Message:

eric@touchy:/tmp/npmz/npm-user$ npm install --cache /tmp/brand-new-cache
npm ERR! code 128
npm ERR! command failed
npm ERR! command git clone --mirror -q ssh://git@github.com/shexSpec/shexTest.git /tmp/brand-new-cache/_cacache/tmp/git-clone-e421e02b/.git
npm ERR! fatal: destination path '/tmp/brand-new-cache/_cacache/tmp/git-clone-e421e02b/.git' already exists and is not an empty directory.

npm ERR! A complete log of this run can be found in:
npm ERR!     /tmp/brand-new-cache/_logs/2021-04-25T16_32_24_722Z-debug.log

The real prob had nothing to do with the cache, but simply that the master branch was renamed to main (which makes this a timely UI experience to improve).

Related issue:
If you change to an existent branch (e.g. main), npm i, change back, and npm i again, you see no error. The package-lock.json entry was changed to "shex-test": "github:shexSpec/shexTest#master" but the node_modules entry appeared to stay on main. While playing with this, i had to reset to square 1 with rm -rf node_modules/ package-lock.json /tmp/brand-new-cache/ to get around this overly agreeable behavior.

[darcyclarke]

Action: determine where/when to throw error for non-existent branch

[lukekarrys]

This will be fixed when pacote@11.3.5 lands in the release on 2021-07-15.

[ondrejsova]

still getting this error on 8.19.2 when using a commit hash

[DePasqualeOrg]

I was also getting this error on npm 10.9.0 when installing packages from GitHub with or without a commit hash. The error message is not helpful, because in fact the problem was that a dependency specified a commit hash that no longer existed in the repo.