[emacs]: snapshots against latest versions

[Cayetano Santos]

Hi Guix,

  Following a recent patch to an snapshot of an emacs package
  (emacs-mastodon), where latest stable (tagged) release dates back from
  a long time, the question of whether to send patches for non stable
  (tagged) versions is pertinent or not.

  Of course, the answer is clear: we only package stable. Guix manual
  (22.4.3 Version Numbers) clearly states that "We usually package only
  the latest version of a given free software project ... Occasionally,
  we package snapshots of upstream’s version control system (VCS)
  instead of formal releases.  This should remain exceptional.". Fine
  with that.

  Now, regarding emacs-xyz packages, the situation is a bit ambiguous.
  We have (old?) (tagged) releases, as well as snapshots. What is the
  rule to follow when we contribute ? At what point in time do we
  consider we may submit patches for snapshots ? With which frequency ?
  Do we consider number or relevance of commits since latest version ?
  Do we base our decision on time elapsed ? Simply put, as for now, we
  have a mix of melpa-stable and melpa: when one may decide to forget
  stable and move forward to latest ? Of course, this is author’s role,
  but I’m wondering how subjective all of this is, and how this might
  impact quality of provided packages.

Best,

Cayetano