This commit is a leftover from #485. I don't really need it, sinse I ended up using `search({...})` instead of #485's `list_packages()` + `highest_version(package_releases())`. I'll look into `parse_version()`, though I don't  feel good about changing this function for some reason (0922f8135240210b270cf2c2665561f85feb3a8a) :)