Semi-automatic update generated by https://github.com/ryantm/nix-update tools.
This update was made based on information from https://repology.org/metapackage/mbuffer/versions.
These checks were done:
- built on NixOS
- ran `/nix/store/sjlbs2k9114xlxalqcz2n0jj90lvik07-mbuffer-20180318/bin/mbuffer -h` got 0 exit code
- ran `/nix/store/sjlbs2k9114xlxalqcz2n0jj90lvik07-mbuffer-20180318/bin/mbuffer --help` got 0 exit code
- ran `/nix/store/sjlbs2k9114xlxalqcz2n0jj90lvik07-mbuffer-20180318/bin/mbuffer -V` and found version 20180318
- ran `/nix/store/sjlbs2k9114xlxalqcz2n0jj90lvik07-mbuffer-20180318/bin/mbuffer --version` and found version 20180318
- found 20180318 with grep in /nix/store/sjlbs2k9114xlxalqcz2n0jj90lvik07-mbuffer-20180318
- directory tree listing: https://gist.github.com/5b88f842903984d6134c96d89c2169de
Negative reasoning like `allBut` is a bad idea with an open world of
platforms. Concretely, if we add a new, quite different sort of
platform, existing packages with `allBut` will claim they work on it
even though they probably won't.
