dontStrip has no effect on Haskell packages #43506
Description
Issue description
Passing dontStrip = true; to a Haskell package has no effect, the resulting binary is stripped.
Steps to reproduce
% file $(nix-build --expr 'with import <nixpkgs> {}; haskell.lib.overrideCabal haskellPackages.hello (old: { dontStrip = true; })')/bin/hello
/nix/store/qqf2c5zq5dqs69vhf7lal08kvb420nwz-hello-1.0.0.2/bin/hello: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/2kcrj1ksd2a14bm5sky182fv2xwfhfap-glibc-2.26-131/lib/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, stripped
Technical details
% nix-shell -p nix-info --run 'nix-info -m'
- system: `"x86_64-linux"`
- host os: `Linux 4.13.0-43-generic, Ubuntu, 16.04.4 LTS (Xenial Xerus)`
- multi-user?: `no`
- sandbox: `no`
- version: `nix-env (Nix) 2.0.4`
- channels(niklas): `"nixpkgs-18.03.132865.411cc559c05, unstable-18.09pre145679.dae9cf6106d, nixos-17.03-17.03.873.0c041520c3"`
- nixpkgs: `/home/niklas/.nix-defexpr/channels/nixpkgs`
CC @peti