Bugfix not unlink generic cover on upload

cps/editbooks.py

@@ -862,6 +862,7 @@ def upload():
                 new_coverpath = os.path.join(config.config_calibre_dir, db_book.path, "cover.jpg")
                 try:
                     copyfile(coverfile, new_coverpath)
+                    if meta.cover:
                         os.unlink(meta.cover)
                 except OSError as e:
                     log.error("Failed to move cover file %s: %s", new_coverpath, e)