bug#17970: log-edit creates unwanted ChangeLog buffers

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Wed, 09 Jul 2014 03:09:23 -0400
> 
> Perhaps log-edit-changelog-entries should not bother visiting
> non-existent files.

That wouldn't be TRT when starting a new repository, or a new
directory in an existing one.

It sounds like a user option is in order.  In addition, if the ignore
file mentions ChangeLog, the command could deduce automatically what
is TRT.