parallel compiler: static mut refs in lib not reproducible

followup https://github.com/rust-lang/rust/issues/140413 :3
we still have problems with --crate-type lib

I tried this code:

#![crate_type="lib"]
static mut TEST: &'static mut [isize] = &mut [1];
static mut TEST_RAW: *mut [isize] = &mut [1isize] as *mut _;
pub fn main() {}

rustc --edition=2024 -Zremap-cwd-prefix=reproducible_dir --cap-lints=warn -Ccodegen-units=1 -Clink-dead-code=true -Zthreads=30 -o out c.rs >& /dev/null ; md5sum out

I expected to see this happen: equal md5sums

Instead, this happened:flipflopping md5s

479f094c3654ecbd0f7fb298a98c12e6  out
0e8d752e35f181aae67e3c4b925028bd  out
0e8d752e35f181aae67e3c4b925028bd  out
479f094c3654ecbd0f7fb298a98c12e6  out
479f094c3654ecbd0f7fb298a98c12e6  out
479f094c3654ecbd0f7fb298a98c12e6  out
479f094c3654ecbd0f7fb298a98c12e6  out
0e8d752e35f181aae67e3c4b925028bd  out
479f094c3654ecbd0f7fb298a98c12e6  out
0e8d752e35f181aae67e3c4b925028bd  out
479f094c3654ecbd0f7fb298a98c12e6  out
0e8d752e35f181aae67e3c4b925028bd  out
0e8d752e35f181aae67e3c4b925028bd  out
0e8d752e35f181aae67e3c4b925028bd  out
479f094c3654ecbd0f7fb298a98c12e6  out
479f094c3654ecbd0f7fb298a98c12e6  out
0e8d752e35f181aae67e3c4b925028bd  out
479f094c3654ecbd0f7fb298a98c12e6  out

Meta

rustc --version --verbose:

rustc 1.100.0-nightly (5db7f4be8 2026-09-01)
binary: rustc
commit-hash: 5db7f4be8a36c1b8ae19299469e2be2b0f052c21
commit-date: 2026-09-01
host: x86_64-unknown-linux-gnu
release: 1.100.0-nightly
LLVM version: 23.1.0

Start by reproducing the reported rustc command with c.rs, including --crate-type lib, -Zthreads=30, and the other listed flags, then compare repeated md5sum results for out. Done means the compiler produces identical output artifacts across repeated builds for this example.