feat: allow version pinning & arbitrary downgrades via `RUSTUP_VERSION` #2248

Set up job

Clone repo

Acquire tags for the repo

Display the current git status

Prep cargo dirs

Set environment variables appropriately for the build

Skip tests

Cache cargo registry and git trees

Get rustc commit hash

Cache cargo build

Install Rustup using ./rustup-init.sh

Ensure Stable is up to date

Ensure we have our goal target installed

Determine which docker we need to run in

Fetch the base docker images from rust-lang/rust

24s

Maybe build a docker from there

11s

Run the build within the docker image

Upload the built artifact

Ensure that awscli is installed

Prepare the dist

Deploy build to dev-static dist tree for release team

Configure AWS credentials

Deploy build to rustup-builds bucket for release team

Clear the cargo caches

Post Cache cargo build

Post Cache cargo registry and git trees

Post Clone repo

Complete job

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