def gitmtime
    # find file extension
    filepath=@item[:content_filename]
    str=`git -1 log --format='%ci' -- #{filepath}`
    # puts '#############'
    # puts "item #{filepath}"
    # puts "str #{str}"
    # puts '#############'
    if str == ""
        return @item.mtime
    else
        return DateTime.parse( str )
    end
end