def jimfile=(file)
      @jimfile = file.is_a?(Pathname) ? file.read : file
      # look for old jimfile
      if @jimfile =~ /^\/\//
        logger.warn "You're Jimfile is in a deprecated format. Run `jim update_jimfile` to convert it."
        parse_old_jimfile
      else
        parse_jimfile
      end
      @jimfile
    end
def jimfile=(file)
      @jimfile = file.is_a?(Pathname) ? file.read : file
      # look for old jimfile
      if @jimfile =~ /^\/\//
        logger.warn "You're Jimfile is in a deprecated format. Run `jim update_jimfile` to convert it."
        parse_old_jimfile
      else
        parse_jimfile
      end
      @jimfile
    end
create a new bundler instance passing in the Jimfile as a `Pathname` or a
 string. `index` is a Jim::Index
 Set the Jimfile and parse it. If `file` is a `Pathname` read it as a string.
 If it's a string assume that its in the Jimfile format.