devpi-client: fix build
devpi-client: fix build

Upstream has already patched this, but haven't done a release yet.
https://github.com/devpi/devpi/commit/185072fcc6f927232cd4bc12b55b9bdbf4b72968

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs