[MERGE] Support logging single merge revisions with short and line log formatters.

[Alexander Belchenko]

Alexander Belchenko has voted tweak.
Status is now: Conditionally approved
Comment:
I want to note that following code is incorrect. It was incorrect before 
and still incorrect now:

     if to_file is None:
         to_file = codecs.getwriter(user_encoding)(sys.stdout,
                                                   errors='replace')

You should not use user_encoding unconditionally.
If bzrlib want to create wrapper around stdout it should use 
osutils.get_terminal_encoding().

This patch is not about terminal encoding. But Kent [accidentally] 
touched this code. So I think this piece of code should be fixed as well 
now. This piece of code does not have proper test before, so I'm not 
intended to write new one now.

If no one has objection, I'll tweak the code in question and merge it.

Martin, it's OK to merge it for 1.0?

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C474199E4.9030902%40gmail.com%3E