Use ISO 8601 dates in Portfile comments

[Ryan Schmidt]

On Apr 7, 2019, at 13:25, Christopher Chavez wrote:

> Currently, comments in Portfiles containing dates, such as for when remove something in the future, are specified in whichever scheme preferred by the port maintainer or whoever inserted the date. Some of these schemes are region-specific (e.g. mm/dd/yyyy used in the US) and potentially ambiguous.
> 
> With MacPorts being an international project, would it be preferable for MacPorts to exclusively use ISO 8601 dates (yyyy-mm-dd) for these purposes? Does that impose too much on maintainers? The primary advantage of doing this will be that it will be easier to search for any dates in Portfiles. I am willing to initiate pull request(s) to convert existing non-ISO 8601 examples I encounter.
> 
> Also, would it be preferable to insist on a consistent exact phrase for such comments: “Remove after yyyy-mm-dd”?

We already use YYYYMMDD dates in the version field of ports where upstream hasn't assigned a version number. Using that same format for comments about when an obsolete port can be removed seems reasonable.