"Today, Google has improved its Robots.txt analysis tool to better recognize sitemap declarations and relative URLs.
Google's new and improved version of the robots.txt file now tells a site owner or webmaster whether the sitemap's URL and scope are valid.
According to Google, overall testing can also be done against relative URLs with a lot less typing.
Line reporting is also better too. Webmasters now will be told of multiple problems per line if they exist, unlike Google's earlier versions which only reported the first problem encountered.
Google has also made other general improvements to the robots.txt analysis tool and its overall validation."