python27Packages.youtube-dl: 2018.03.26.1 -> 2018.04.16

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/youtube-dl/versions.

These checks were done:

- built on NixOS
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/.youtube-dl-wrapped -h’ got 0 exit code
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/.youtube-dl-wrapped --help’ got 0 exit code
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/.youtube-dl-wrapped --version’ and found version 2018.04.16
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/youtube-dl -h’ got 0 exit code
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/youtube-dl --help’ got 0 exit code
- ran ‘/nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16/bin/youtube-dl --version’ and found version 2018.04.16
- found 2018.04.16 with grep in /nix/store/3dkc0vhb4v2fyagm0p33r54f6j89sjb0-youtube-dl-2018.04.16
- directory tree listing: https://gist.github.com/359ce5add8ebf04a1dfe79aecb499137