Fix segfault in nix-copy-closure
Fix segfault in nix-copy-closure

dtzWill/nix,ehmry/nix,peti/nix,bennofs/nix,vcunat/nix,vcunat/nix,bennofs/nix,rycee/nix,shlevy/nix,pikajude/nix,NixOS/nix,zimbatm/nix,rycee/nix,dtzWill/nix,rycee/nix,dezgeg/nix,zimbatm/nix,NixOS/nix,layus/nix,ehmry/nix,bennofs/nix,ysangkok/nix,ysangkok/nix,dezgeg/nix,NixOS/nix,rycee/nix,dezgeg/nix,bennofs/nix,layus/nix,layus/nix,ehmry/nix,peti/nix,zimbatm/nix,dezgeg/nix,shlevy/nix,ehmry/nix,peti/nix,dtzWill/nix,shlevy/nix,pikajude/nix,vcunat/nix,ysangkok/nix,dtzWill/nix,dezgeg/nix,vcunat/nix,rycee/nix,ehmry/nix,peti/nix,pikajude/nix,dtzWill/nix,NixOS/nix,ehmry/nix,layus/nix,shlevy/nix,peti/nix,NixOS/nix,shlevy/nix,layus/nix,zimbatm/nix