1.28.0 does not accept components separated by spaces

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

Hello,

At work, we use

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --no-modify-path -y --default-toolchain nightly-2025-02-11 -c cargo rustc rust-src

to install a specific version of rust in our CI environment but since latest version (ie: v1.28.0), it fails with:

$ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --no-modify-path -y --default-toolchain nightly-2025-02-11 -c cargo rustc rust-src
info: downloading installer
error: error: unexpected argument 'rustc' found

Usage: rustup-init[EXE] [OPTIONS]

For more information, try '--help'.

After reading https://blog.rust-lang.org/2025/03/02/Rustup-1.28.0.html I understand that some amount of backward incompatible changes have been released (with very short notice) but I don't understand:

1. Why it impacts my current workflow since I am specifically asking for a toolchain
2. How to fix it. I am absolutely able to fix my CI configuration, but at the moment, I have no idea how and the error message doesn't provide any kind of help.

Thank you in advance for your help 👍

Steps

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --no-modify-path -y --default-toolchain nightly-2025-02-11 -c cargo rustc rust-src

Possible Solution(s)

No response

Notes

No response

Rustup version

1.28.0

Installed toolchains

nightly-2025-02-11

OS version

Linux

Reproduce the documented rustup-init command on Linux with rustup 1.28.0, focusing on the -c cargo rustc rust-src arguments and the unexpected-argument error. Trace the installer’s command-line parsing entry point and existing help behavior; done means the documented space-separated components work again or the command reports a clear, actionable correction.