Problem
If a patch section contains a specification with a "path" override, cargo vendor does not vendor these content to the vendor directory.

Steps
Add a patch statement such as:

[patch.crates-io]
mycrate = { path = "../mycrate" }

Then run cargo vendor

Possible Solution(s)
Cargo vendor should copy the content of the crate (excluding git artefacts) to the vendor directory.

Notes

cargo 1.50.0 (f04e7fa 2021-02-04)