abcmidi: 2018.04.24 -> 2018.05.02

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/abc2midi -h’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/midi2abc -h’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/midi2abc --help’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/abc2abc -h’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/mftext -h’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/mftext --help’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/mftext help’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/yaps -h’ got 0 exit code
- ran ‘/nix/store/cw3374p08xihakpimdka1afpa8s0kqh9-abcMIDI-2018.05.02/bin/abcmatch -h’ got 0 exit code
- directory tree listing: https://gist.github.com/ab3313bb3097bf194e4ac83d6cc0b9bc