git-svn: speed up blame command 'git svn blame' now uses the 'git cat-file --batch' command to speed up resolving SVN revision number out of commit SHA by removing fork+exec overhead. [ew: enforced 80-column line wrap] Signed-off-by: Boris Byk <boris.byk@gmail.com> Acked-by: Eric Wong <normalperson@yhbt.net>