The chown ran before rustup and cargo-audit were installed, so everything
those created under RUSTUP_HOME/CARGO_HOME was left root-owned: only the two
empty directories existing at chown time belonged to ci_build. Measured on the
previous snapshot: 18350 root-owned paths, including cargo/registry. Every Rust
build with external dependencies failed with "Permission denied (os error 13)".
Re-assert ownership after the installs, and assert writability rather than mere
existence -- test -x on the binaries could not catch this, so a broken template
passed its own build and failed in consumers' jobs instead.
Also wire the toolchain for non-login shells. The orchestrator runs build
commands via paramiko exec_command + `sh -c`, which never sources
/etc/profile.d, so profile.d alone was not enough: add RUSTUP_HOME/CARGO_HOME
to /etc/environment (read by pam_env at SSH session open) and symlink the
rustup proxies into /usr/local/bin.
Simone
20e573ccef