Describe the problem you are trying to solve
I want to check in some subset of my cargo configuration into version control (e.g., aliases useful to all devs), but not others (e.g., parts that hold custom patches, rustflags, or other local build options).

Describe the solution you'd like
I would like to be able to split my configuration file into multiple files, and then only check in some of them.

Notes
Currently, my options are:

• Check in the entire cargo configuration into version control, and thus impose my local build configuration on other devs.
• Don't check in the cargo configuration and find an out-of-band mechanism for distributing common project configuration.
• Nest my project in an extra subdirectory and place the local configuration in a parent directory and the shared configuration in the project directory itself.

None of these are ideal. It'd be nice if cargo supported something like a .cargo/config.toml.d/ directory that could then contain any number of configuration files that are merged.