Don't show size mismatch warnings for zero-size files

whipper/program/cdparanoia.py

@@ -380,7 +380,7 @@ def _done(self):
                                                     "File is empty, "
                                                     "expected size %d" % (
                                                         expected )))
-        if size != expected:
+        elif size != expected:
             # FIXME: handle errors better
             logger.warning('file size %d did not match expected size %d',
                            size, expected)