...

src/calibre/ebooks/mobi/output.py

@@ -58,7 +58,7 @@ class MOBIOutput(OutputFormatPlugin):
             except ImportError:
                 import Image as PILImage
 
-            raw = StringIO(server_resources['calibre.png'])
+            raw = StringIO(server_resources['calibre_banner.png'])
             im = PILImage.open(raw)
             of = StringIO()
             im.save(of, 'GIF')

src/calibre/library/database2.py

@@ -1374,7 +1374,7 @@ class LibraryDatabase2(LibraryDatabase):
         self.set_path(id, True)
         self.conn.commit()
         self.set_metadata(id, mi)
-        if cover:
+        if cover is not None:
             self.set_cover(id, cover)
         return id