Bumping Rust past 1.78 breaks nix CI build

[ifd3f]

Describe the bug

This problem is related to #151

Based on the results of #155 it seems that 1.78 is the last version that won't break.

To Reproduce

Apply the following change onto #155:

diff --git a/nix/cross-helpers.nix b/nix/cross-helpers.nix
index eb4244a..c7add9e 100644
--- a/nix/cross-helpers.nix
+++ b/nix/cross-helpers.nix
@@ -27,7 +27,7 @@ in rec {
     overlays = [ rust-overlay.overlays.default ];
   };
 
-  baseToolchain = pkgs.rust-bin.stable."1.78.0".default;
+  baseToolchain = pkgs.rust-bin.stable."1.79.0".default;
 
   supportedSystems = if hostInfo.kernel.name == "linux" then [
     "aarch64-linux"

then run nix build

Expected behavior

Successful build

Log files

> nix build
error: builder for '/nix/store/zv39c6lyjl5268frz1m37vpxh9qzffxd-caligula-0.4.7.drv' failed with exit code 101;
       last 25 log lines:
       >   cargo:rerun-if-env-changed=AR_x86_64-unknown-linux-musl
       >   AR_x86_64-unknown-linux-musl = None
       >   cargo:rerun-if-env-changed=AR_x86_64_unknown_linux_musl
       >   AR_x86_64_unknown_linux_musl = None
       >   cargo:rerun-if-env-changed=TARGET_AR
       >   TARGET_AR = None
       >   cargo:rerun-if-env-changed=AR
       >   AR = Some("ar")
       >   cargo:rerun-if-env-changed=ARFLAGS_x86_64-unknown-linux-musl
       >   ARFLAGS_x86_64-unknown-linux-musl = None
       >   cargo:rerun-if-env-changed=ARFLAGS_x86_64_unknown_linux_musl
       >   ARFLAGS_x86_64_unknown_linux_musl = None
       >   cargo:rerun-if-env-changed=TARGET_ARFLAGS
       >   TARGET_ARFLAGS = None
       >   cargo:rerun-if-env-changed=ARFLAGS
       >   ARFLAGS = None
       >   cargo:rustc-link-lib=static=bz2
       >   cargo:rustc-link-search=native=/build/caligula-src/target/x86_64-unknown-linux-musl/release/build/bzip2-sys-dd221a21b4deb349/out/lib
       >
       >   --- stderr
       >   thread 'main' panicked at /nix/store/kbphjzq0jwd3g6yk4g9q9nnwy9bl3v3s-crates-io-dependencies/bzip2-sys-0.1.11+1.0.8-736a955f3fa7875102d57c82b8cac37ec45224a07fd32d58f9f7a186b6cd4cdc/build.rs:44:64:
       >   called `Result::unwrap()` on an `Err` value: Os { code: 13, kind: PermissionDenied, message: "Permission denied" }
       >   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
       > warning: build failed, waiting for other jobs to finish...
       > [naersk] cargo returned with exit code 101, exiting
       For full logs, run 'nix log /nix/store/zv39c6lyjl5268frz1m37vpxh9qzffxd-caligula-0.4.7.drv'.