> Technically we could still avoid set-environment-variable! if we have
> a srfi-39 environment parameter and make the "spawn-process" procedure
> (whatever its name is) look at this too in addition to :environment,
> but I'm probably complicating things unnecessarily.

This would mean that C code running via FFI and using libc getenv() has
a different view of the environment variables than Scheme code does. It
also means that any Schemes implementing SRFI 98
`get-environment-variable` need to change that implementation to take
the environment parameter into account.

This envar business ended up being a bit more complex than initially
thought :)