Chris Lee authored Apr 04, 2014 and Bastien Nocera committed Apr 07, 2014

If the OPF file is in the root dir, g_path_get_dirname returns "."
instead of an empty string. This results in an invalid key for the cover
image, because it looks like "./OEBPS/cover_path.jpg" instead of
"OEBPS/cover_path.jpg" and then unzipping for that path fails.