cargo update: repo updated twice

[matthiaskrgr]

Problem
when running cargo update in the rustc or rls repo, it looks like the clippy repo inside the cache is updated twice. This seems redundant.

  Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rust-clippy`
    Updating git repository `https://github.com/rust-lang/rust-clippy`
      Adding addr2line v0.12.1
    Updating anyhow v1.0.28 -> v1.0.31

Steps

1. cargo update

Possible Solution(s)
Don't update the git repo two times back-to-back.

Notes

Output of cargo version:
cargo 1.45.0-nightly (cb06cb269 2020-05-08)

Note: It doesn't look like cargo update -vvvvv has any additional effect :/

[ehuss]

The CARGO_LOG=debug environment variable is usually the best way to get more information.

In this case, there are two separate revisions of rust-clippy in the graph (probably a mistake in the RLS repo).

Cargo doesn't know that the rev is a precise commit hash, so it takes a conservative approach of making sure the repo is updated before checking what the actual rev is.

There are some wonky issues with how Cargo is creating GitSources. Sometimes they are unique per revision, and sometimes they are shared, causing various bugs like #7841 and #8101. This looks like a similar situation where there are two GitSources where one would suffice.

[epage]

This looks to be a duplicate of #6921, closing in favor of that. If there is something I missed, let us know!