Propagate existing VCS to subprojects

[Iniesta8]

With this post, when creating a new project within an existing project, any existing VCS is reused by creating a matching ignore file in the new subfolder. (see issue #6357)

• If a VCS is explicitly given, e. g. by config or by command line option a new VCS environment will be initialized
• If there is no VCS explicitly given and we are not in an existing VCS environment, Git will be initialized
• If there is no VCS explicitly given and we are in an existing VCS, we propagate this VCS into the subproject

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @ehuss (or someone else) soon.

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[ehuss]

Thanks for the PR, but I think this is working as intended. If new packages are created within a workspace, I wouldn't want it to create extra .gitignore files. I think this is somewhat fundamental to cargo new not knowing the intention of the user, so it can be difficult for it to make a choice.

[bors]

☔ The latest upstream changes (presumably #7776) made this pull request unmergeable. Please resolve the merge conflicts.

[ehuss]

I'm going to close this for now. Feel free to follow up on the issue tracker. However, I'm not sure if there is a clear path forward since Cargo doesn't really know how the new project is intended to be used (such as in a workspace or not). This also creates nested repositories which doesn't seem like the right behavior.