Re-requesting reviews on GitHub

[Dr. Matthias St. Pierre]

Independently of the new 'approval: *' state labelling I was wondering whether it wouldn't
be a good idea to adopt the habit of explicitly requesting a re-review from the other reviewers
after significant changes, using the mechanism provided by GitHub (i.e. the button with the two
circling arrows next to the reviewer entry). In that way, outdated reviews would become more
visible, and outdated reviews wouldn't be addrev'ed to the commit message when merging,
unless they are renewed before the 24h grace period expires.  For nit changes, the current informal
way of re-approval could be kept of course.

What's your opinion?

Matthias