bug#22978: 25.0.92; log-view-diff: TMM required for non-consecutive revisions

[Bob Rogers]

   From: Eli Zaretskii <eliz@gnu.org>
   Date: Wed, 20 Jun 2018 19:25:17 +0300

   . . .

   My problem with the change is that there seems to be no escape from
   it.  And since in any buffer, the mark gets set pretty soon after one
   starts to move around, it means users who turn off transient-mark-mode
   will have no reasonable way of diffing the revision at point with the
   previous one.

"C-SPC =" ?

   By contrast, the current behavior allows you to get diffs between
   revisions at region edges by "C-SPC C-SPC" etc.

So that means it's a difference of typing "C-SPC" once for the single
revision versus typing it twice for multiple revisions.  I might argue
that the latter is more backward-compatible, but I don't actually
believe this is worth arguing about.  Sorry for the noise.

                                        -- Bob