Issue description
mktemp fails with too few X's in template on Darwin when tries to create a temporary directory.
Steps to reproduce
$: nix-shell --packages coreutils --run "which mktemp && mktemp -d -t foo"
/nix/store/s28xb9v7xf6axvf4a3av2mnczws2hsdg-coreutils-8.29/bin/mktemp
mktemp: too few X's in template ‘foo’
Technical details
$: nix-shell -p nix-info --run "nix-info -m"
these paths will be fetched (0.01 MiB download, 0.03 MiB unpacked):
/nix/store/aiaqhmk1x114msypcykhi27n6iydrhjm-nix-info
/nix/store/ln5498nmkjkv1ssa2x644czc7x1xwcx6-DarwinTools-1
copying path '/nix/store/ln5498nmkjkv1ssa2x644czc7x1xwcx6-DarwinTools-1' from 'https://cache.nixos.org'...
copying path '/nix/store/aiaqhmk1x114msypcykhi27n6iydrhjm-nix-info' from 'https://cache.nixos.org'...
- system: `"x86_64-darwin"`
- host os: `Darwin 16.7.0, macOS 10.12.6`
- multi-user?: `yes`
- sandbox: `no`
- version: `nix-env (Nix) 2.0`
- channels(root): `"nixpkgs-18.09pre133932.ee28e35ba37"`
- nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixpkgs`
/cc maintainer @edolstra
Issue description
mktempfails withtoo few X's in templateon Darwin when tries to create a temporary directory.Steps to reproduce
Technical details
/cc maintainer @edolstra