Use of an empty string that is used for 'everything matches' is
still warned and Git asks users to use a more explicit '.' for that
instead. The hope is that existing users will not mind this
change, and eventually the warning can be turned into a hard error,
upgrading the deprecation into removal of this (mis)feature. That
is not scheduled to happen in the upcoming release (yet).
The historical argument order "git merge <msg> HEAD <commit>..."
has been deprecated for quite some time, and will be removed in a
future release.
Git 2.12 Release Notes ======================
Backward compatibility notes.