[MERGE] special case the no-args version of revision-info

[Ian Clatworthy]

Michael Hudson wrote:
> Reading this post:
> 
> http://blog.orebokech.com/2008/03/emacs-in-bzr-initial-impressions.html
> 
> I was prompted to look at the implementation of version-info.  It seems
> to be a bit whole-history happy: RevisionSpec.in_branch calls
> revsion_history() and the command implementation calls
> get_revid_to_revno_map().
> 
> This bundle just makes it really fast for the no-arg case.  Perhaps it
> would be better to improve the interpretation of "revno:-$SMALLINT".

Trying your patch on bzr.dev, it doesn't seem to make much difference to
the results of 'time bzr version-info'. Maybe I'm doing something wrong.
What speed-up are you seeing?

Ian C.