Commits that implicitly close PRs do not remember doing so

[Lawrence Velázquez]

> On Dec 6, 2016, at 10:33 AM, Rainer Müller <raimue at macports.org> wrote:
> 
> (e) add "Closes: #XYZ" to the commit message

When commits close PRs implicitly (by merging the PR branch) instead of explicitly (by using "closes #XYZ" in the message), the PR is remembered internally by GitHub and displayed on the website but is not recorded in our Git repository. If we ever migrate off GitHub, we would presumably lose this information.

Should we consider this a problem?

vq