Cargo does not track env!("FOO") for rebuilding

[Mark-Simulacrum]

Given the code below, I would expect Cargo to rebuild the crate when FOO changes, but this currently does not happen. I don't know if Cargo currently has enough information to handle this, though.

fn foo() -> &'static str {
    env!("FOO")
}

[alexcrichton]

Thanks for the report! I think this is a dupe of #2776, so I'm going to close it in favor of that

[Imberflur]

For future readers, cargo now tracks these via #8421