RUSTC_BOOTSTRAP on crates.io

shnatsel@shnatsel-desktop ~/C/c/crates> rg --iglob '*.rs' -F 'RUSTC_BOOTSTRAP' 2>/dev/null | cat
hash-table-0.2.3/build.rs:    println!("rustc-env=RUSTC_BOOTSTRAP=1");
obfstr-0.1.0/build.rs:	println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
containers-0.9.6/build.rs:    println!("rustc-env=RUSTC_BOOTSTRAP=1");
datatest-0.6.2/build.rs:    println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
rustc-ap-rustc_feature-652.0.0/lib.rs:        let bootstrap = std::env::var("RUSTC_BOOTSTRAP").is_ok();
fast-rustc-ap-rustc_feature-1.0.0/lib.rs:        let bootstrap = std::env::var("RUSTC_BOOTSTRAP").is_ok();
libtest-0.0.1/lib.rs:    let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
encoding_rs-0.8.22/build.rs:    // This does not enable `RUSTC_BOOTSTRAP=1` for `packed_simd`.
encoding_rs-0.8.22/build.rs:    println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
i-o-0.4.4/build.rs:    println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
simd-0.2.4/build.rs:    println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
ptr-0.2.1/build.rs:    println!("rustc-env=RUSTC_BOOTSTRAP=1");
syntex_syntax-0.59.1/src/feature_gate.rs:        let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
msiz_rustc-ap-syntax-3.0.0/feature_gate/check.rs:        let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
syntex_syntax2-0.0.2/src/feature_gate.rs:        let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
sccache-0.2.13/src/compiler/rust.rs:            .env("RUSTC_BOOTSTRAP", "1"); // TODO: this is fairly naughty
tester-0.7.0/src/cli.rs:    let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
substrate-wasm-builder-1.0.9/src/lib.rs:		// `RUSTC_BOOTSTRAP` tells a stable compiler to behave like a nightly. So, when this env
substrate-wasm-builder-1.0.9/src/lib.rs:		env::var("RUSTC_BOOTSTRAP").is_ok() ||
pyoxidizer-0.7.0/src/project_building.rs:        envs.push(("RUSTC_BOOTSTRAP", "1".to_string()));
vkcargo-0.45.1/tests/testsuite/standard_lib.rs:                    let is_sysroot_crate = env::var_os("RUSTC_BOOTSTRAP").is_some();
cargo-0.43.1/tests/testsuite/standard_lib.rs:                    let is_sysroot_crate = env::var_os("RUSTC_BOOTSTRAP").is_some();
vkcargo-0.45.1/src/cargo/core/features.rs:    if let Ok(staging) = env::var("RUSTC_BOOTSTRAP") {
cargo-semverver-0.34.0/src/cargo/core/features.rs:    if let Ok(staging) = env::var("RUSTC_BOOTSTRAP") {
cargo-0.43.1/src/cargo/core/features.rs:    if let Ok(staging) = env::var("RUSTC_BOOTSTRAP") {
vkcargo-0.45.1/src/cargo/core/compiler/mod.rs:        // RUSTC_BOOTSTRAP allows unstable features on stable.
vkcargo-0.45.1/src/cargo/core/compiler/mod.rs:            .env("RUSTC_BOOTSTRAP", "1");
cargo-0.43.1/src/cargo/core/compiler/mod.rs:        // RUSTC_BOOTSTRAP allows unstable features on stable.
cargo-0.43.1/src/cargo/core/compiler/mod.rs:            .env("RUSTC_BOOTSTRAP", "1");