Strip 0 bytes from HTML before parsing

src/calibre/ebooks/conversion/preprocess.py

@@ -157,6 +157,7 @@ class HTMLPreProcessor(object):
     def __call__(self, html, remove_special_chars=None):
         if remove_special_chars is not None:
             html = remove_special_chars.sub('', html)
+        html = html.replace('\0', '')
         if self.is_baen(html):
             rules = []
         elif self.is_book_designer(html):