mostly to avoid long lines (>= 80)

checkdoc complained that `uses' should be in imperative form...

With this our *vc-dir* looks more like the others. Instead of showing something like stage:edit we only add `M', `D' or `A' (the got status flags), and so we don't need the ugly hack too.

Emacs 27.1 is a prerequisite because of flatten-list, otherwise it should run on 25.1 onwards.