Prompt for merge message?

["Todd A. Jacobs" <nospam+listmail@codegnome.org>]

I often find myself using "--no-ff -m foo" for merging short-lived
branches, because the merge commit usually needs to say something
about having finished a feature rather than referring to a branch that
will be deleted shortly anyway. However, it's a little annoying to
have to always write the commit message on the command-line,
especially in cases where a more expository multi-line message would
be useful.

Is there currently a way to get git to prompt for the merge message,
rather than using the default or requiring the -m flag? If not, isn't
this a common-enough use case to have that ability added to the merge
function?