`cargo clippy --all-targets` issues diagnostics for library crate twice

[zackw]

Given a crate containing this file as src/lib.rs

pub fn demo() -> &'static str {
    return "demo";
}

and at least one file in tests that does use name_of_crate::demo, cargo clippy --all-targets will diagnose the needless_return twice in a row. If you use cargo --verbose it's clear that the clippy-driver program has been invoked twice (once with --test and once without) and each invocation is reporting the lint, but without that, it looks like clippy is repeating itself for no reason.

[GeeWee]

Can confirm that it also seems like clippy fix will attempt to diagnose and fix the problem multiple times within one invocation with --all-targets, (if you recreate the issue right after it was fixed)