musl and darwin support UTF-8 locales without any extras. As a result
unzip can unpack UTF-8 filenames there as is. But on glibc without
locale archive presence files get mangled as:
deps/αβ -> deps/#U03b1#U03b2
This makes `fetchzip` fixed-output derivations unstable.
Tested this change to fail in `coq.src` which was generated in system
that mangles UTF-8 symbols:
$ nix build -f. coq.src --rebuild -L
source> trying https://github.com/coq/coq/archive/V8.15.2.zip
source> % Total % Received % Xferd Average Speed Time Time Time Current
source> Dload Upload Total Spent Left Speed
source> 0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0
source> 100 8945k 100 8945k 0 0 1513k 0 0:00:05 0:00:05 --:--:-- 1989k
source> unpacking source archive /build/V8.15.2.zip
error: hash mismatch in fixed-output derivation '/nix/store/hrnyykm7wgw8vxisgq7hc2bg5gr0y6s8-source.drv':
specified: sha256-h81nFqkuvZkMR7YLHy7laTq5yOhjMW+w6rYzncxvyD4=
got: sha256-DTspmwyD3Evl1CUmvUy2MonbLGUezvsHN3prmP9eK2I=
Note: it means that some of existing caches for fixed output
derivations become incorrect. It should not break already cached
tarballs on cache.nixos.org thus the impact should not be widespread.
Sergei Trofimovich
ffb456ae61