Vendoring a project with no dependencies leads to misleading output

[Firstyear]

Problem
When using cargo vendor on a project with no deps, the output is misleading:

 cargo vendor
To use vendored sources, add this to your .cargo/config for this project:

[source.vendored-sources]
directory = "/Users/william/development/389ds/ds/src/libsds/vendor"

Possible Solution(s)
This should state:

• No dependencies were found
• Suggest no changes to .cargo/config

Output of cargo version:
1.38, 1.38

[Firstyear]

To help explain - because there were no dependencies no vendor directory was created, but it looked like cargo vendor had "done something" suggesting to add a vendor dir to your configuration. This mislead me to thinking cargo vendor was "not working" until I realised that the reason was the single sub-projects lack of dependencies.

What also then would help is if the output says what command flags are needed to cargo build to use the vendored sources, because I'm using --offline --locked, but still not sure that's correct ....

edit: hit update too soon.