Only copy has_cover and id if they exist

src/calibre/ebooks/metadata/book/base.py

@@ -7,6 +7,7 @@
 
 import copy
 import traceback
+from contextlib import suppress
 
 from calibre import prints
 from calibre.constants import DEBUG
@@ -232,8 +233,10 @@ def deepcopy_metadata(self):
         m = Metadata(None)
         object.__setattr__(m, '_data', copy.deepcopy(object.__getattribute__(self, '_data')))
         # Also copy these two top-level attributes as they can appear in templates.
-        object.__setattr__(m, 'id', copy.copy(self.get('id')))
-        object.__setattr__(m, 'has_cover', copy.copy(self.get('has_cover')))
+        with suppress(AttributeError):
+            object.__setattr__(m, 'id', copy.copy(self.__getattribute__('id')))
+        with suppress(AttributeError):
+            object.__setattr__(m, 'has_cover', copy.copy(self.__getattribute__('has_cover')))
         return m
 
     def get(self, field, default=None):