double-checked-cell 2.1.0

# rustc version
rustc 1.50.0-nightly (2225ee1b6 2020-12-11)# docs.rs version
docsrs 0.6.0 (31c864e 2020-11-22)# build log
[INFO] running `Command { std: "docker" "create" "-v" "/home/cratesfyi/workspace/builds/double-checked-cell-2.1.0/target:/opt/rustwide/target:rw,Z" "-v" "/home/cratesfyi/workspace/builds/double-checked-cell-2.1.0/source:/opt/rustwide/workdir:ro,Z" "-v" "/home/cratesfyi/workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/home/cratesfyi/workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "DOCS_RS=1" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "3221225472" "--cpus" "2" "--user" "1001:1001" "--network" "none" "rustops/crates-build-env@sha256:6eabd152ff4036248d66efda456a36cb33d24b7291b33f25f75140726c88da35" "/opt/rustwide/cargo-home/bin/cargo" "+nightly" "rustdoc" "--lib" "-Zrustdoc-map" "--all-features" "-Zunstable-options" "--config=doc.extern-map.registries.crates-io=\"https://docs.rs\"" "-j2" "--" "-Z" "unstable-options" "--resource-suffix" "-20201211-1.50.0-nightly-2225ee1b6" "--static-root-path" "/" "--cap-lints" "warn" "--disable-per-crate-search", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 680fdbcae705a7a927ed950a1f8b2975bb6fcf9ca37cc63d58e2005866ecc853
[INFO] running `Command { std: "docker" "start" "-a" "680fdbcae705a7a927ed950a1f8b2975bb6fcf9ca37cc63d58e2005866ecc853", kill_on_drop: false }`
[INFO] [stderr] /opt/crates-build-env/entrypoint.sh: line 7: /etc/hosts: Permission denied
[INFO] [stderr]    Compiling libc v0.2.81
[INFO] [stderr]     Checking cfg-if v1.0.0
[INFO] [stderr]     Checking scopeguard v1.1.0
[INFO] [stderr]     Checking smallvec v1.5.1
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking instant v0.1.9
[INFO] [stderr]     Checking lock_api v0.4.2
[INFO] [stderr]     Checking unreachable v1.0.0
[INFO] [stderr]     Checking parking_lot_core v0.8.1
[INFO] [stderr]     Checking parking_lot v0.11.1
[INFO] [stderr]  Documenting double-checked-cell v2.1.0 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 4.93s
[INFO] running `Command { std: "docker" "inspect" "680fdbcae705a7a927ed950a1f8b2975bb6fcf9ca37cc63d58e2005866ecc853", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "680fdbcae705a7a927ed950a1f8b2975bb6fcf9ca37cc63d58e2005866ecc853", kill_on_drop: false }`
[INFO] [stdout] 680fdbcae705a7a927ed950a1f8b2975bb6fcf9ca37cc63d58e2005866ecc853