Motivation for this change

Maintenance release - security patches for OpenEXR

The 2.2.1 release addresses the known OpenEXR security vulnerabilities, specifically CVE-2017-9110, CVE-2017-9111, CVE-2017-9112, CVE-2017-9113, CVE-2017-9114, CVE-2017-9115, CVE-2017-9116.

Should be backported to 17.09.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

cc @wkennington