Panic while "cleaning up cached downloads"

Problem

» RUST_BACKTRACE=1 cargo b
info: syncing channel updates for 'nightly-2021-10-14-x86_64-apple-darwin'
info: latest update on 2021-10-14, rust version 1.57.0-nightly (dfc5add91 2021-10-13)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: retrying download for 'https://static.rust-lang.org/dist/2021-10-14/rust-std-nightly-x86_64-apple-darwin.tar.xz'
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: cleaning up cached downloads

Caused by:
    No such file or directory (os error 2)', download/src/lib.rs:130:14
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::option::expect_none_failed
   3: rustup::utils::utils::download_file_with_resume
   4: rustup::dist::manifestation::Manifestation::update
   5: rustup::dist::dist::try_update_from_dist_
   6: rustup::install::InstallMethod::install
   7: rustup::toolchain::DistributableToolchain::install_from_dist
   8: rustup::config::Cfg::find_or_install_override_toolchain_or_default
   9: rustup_init::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Steps

1. I run cargo build in a repo with rust-toolchain

Possible Solution(s)

No response

Notes

This seems similar to #2894, but,
a. I am not running a second instance of rustup inadvertently
b. that's marked as fixed?

Rustup version

(I believe this to be the latest & greatest rustup.)

» rustup --version
rustup 1.24.3 (ce5817a94 2021-05-31)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.56.1 (59eed8a2a 2021-11-01)`

Installed toolchains

» rustup show
Default host: x86_64-apple-darwin
rustup home:  /Users/roy/.rustup

installed toolchains
--------------------

stable-x86_64-apple-darwin
nightly-2019-04-11-x86_64-apple-darwin
nightly-2021-03-19-x86_64-apple-darwin
nightly-2021-03-21-x86_64-apple-darwin
nightly-2021-07-24-x86_64-apple-darwin
nightly-2022-02-18-x86_64-apple-darwin
nightly-x86_64-apple-darwin
1.37.0-x86_64-apple-darwin
1.38.0-x86_64-apple-darwin
1.39.0-x86_64-apple-darwin
1.40.0-x86_64-apple-darwin
1.41.0-x86_64-apple-darwin
1.42.0-x86_64-apple-darwin
1.43.1-x86_64-apple-darwin
1.44.1-x86_64-apple-darwin
1.46.0-x86_64-apple-darwin
1.47.0-x86_64-apple-darwin
1.47.0-x86_64-unknown-linux-gnu
1.48.0-x86_64-apple-darwin
1.49.0-x86_64-apple-darwin
1.50.0-x86_64-apple-darwin
1.51.0-x86_64-apple-darwin

active toolchain
----------------

stable-x86_64-apple-darwin (default)
rustc 1.56.1 (59eed8a2a 2021-11-01)

Start at download/src/lib.rs:130 and the rustup::utils::utils::download_file_with_resume stack entry, then reproduce with cargo build in a repository containing rust-toolchain. Done means the cached-download cleanup failure no longer causes a panic and the command reports the download problem appropriately.