BBC-News/wraith — pull request #139 by DaveBlooman (2014-05-28 09:39:23+00:00)
Title: Handle error better

This PR ensures that the compare task works when a diff image isn't created. This can happen when the images aren't the same size, which imagemagick cant handle. In this situation, just writing the file with an invalid string will prompt the user to investigate, but usually, the images should indicate an error with the page.