Thread pool panic "Resource temporarily unavailable"

Verification

• I searched for recent similar issues at https://github.com/rust-lang/rustup/issues?q=is%3Aissue+is%3Aopen%2Cclosed and found no duplicates.
• I am on the latest version of Rustup according to https://github.com/rust-lang/rustup/tags and am still able to reproduce my issue.

Problem

When running the installer on https://rustup.rs/, and entering 1 for default options, rustup panics while downloading stuff.

thread 'main' panicked at /cargo/registry/src/index.crates.io-6f17d22bba15001f/threadpool-1.8.1/src/lib.rs:777:10:
called `Result::unwrap()` on an `Err` value: Os { code: 11, kind: WouldBlock, message: "Resource temporarily unavailable" }

Steps

1. Run curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
2. Choose 1) Proceed with standard installation (default - just press enter)
3. Rustup panics roughly when it starts downloading cargo. rustup-backtrace.txt

Possible Solution(s)

No response

Notes

No response

Rustup version

[ Rustup does not succesfully install. ]

Installed toolchains

[ Rustup does not succesfully install. ]

OS version

Debian 10 (buster), x86_64

Start with the attached rustup-backtrace.txt and the installer path reached after selecting the standard installation option. Investigate the threadpool-1.8.1 panic and its EAGAIN error on Debian 10; done means the installer completes without this panic.