s3cmd does not work from nix-shell (even without --pure)

[anderspapitto]

Issue description/Steps to reproduce

I have s3cmd installed globally via environment.systemPackages

[anders@gurney:~/devel/card-game]
$ s3cmd ls
[anders@gurney:~/devel/card-game]
$ nix-shell -p s3cmd

[nix-shell:~/devel/card-game]$ s3cmd ls
ERROR: SSL certificate verification failure: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:590)

Technical details

[anders@gurney:~/devel/card-game]
$ nixos-version
16.09.git.1ceb6ea (Flounder)
[anders@gurney:~/devel/card-game]
$ nix-env --version
nix-env (Nix) 1.11.2
[anders@gurney:~/devel/card-game]
$ nix-instantiate --eval '<nixpkgs>' -A lib.nixpkgsVersion
"16.09.git.1ceb6ea"

[anderspapitto]

hmm. This appears to be because nix shell is setting SSL_CERT_FILE

[anders@gurney:~/devel/card-game]
$ env | grep SSL
[anders@gurney:~/devel/card-game]
$ nix-shell -p s3cmd

[nix-shell:~/devel/card-game]$ env | grep SSL
SSL_CERT_FILE=/no-cert-file.crt

I'm not sure why that's done in a non --pure shell

[FRidh]

Related are #13744, #15873 and #15571

[FRidh]

Closing this since its a known issue and described in #13744.