Add a special deepcopy that only copies metadata, not the other random attributes that have been added.

src/calibre/devices/prs505/sony_cache.py

@@ -360,7 +360,7 @@ class XMLCache(object):
                 if record is None:
                     record = self.create_text_record(root, i, book.lpath)
                 if plugboard is not None:
-                    newmi = book.deepcopy()
+                    newmi = book.deepcopy_metadata()
                     newmi.template_to_attribute(book, plugboard)
                 else:
                     newmi = book

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

@@ -148,6 +148,11 @@ class Metadata(object):
         object.__setattr__(m, '_data', copy.deepcopy(object.__getattribute__(self, '_data')))
         return m
 
+    def deepcopy_metadata(self):
+        m = Metadata(None)
+        object.__setattr__(m, '_data', copy.deepcopy(object.__getattribute__(self, '_data')))
+        return m
+
     def get(self, field, default=None):
         try:
             return self.__getattribute__(field)

src/calibre/gui2/device.py

@@ -357,7 +357,7 @@ class DeviceManager(Thread): # {{{
                                         f, file=sys.__stdout__)
                             with open(f, 'r+b') as stream:
                                 if cpb:
-                                    newmi = mi.deepcopy()
+                                    newmi = mi.deepcopy_metadata()
                                     newmi.template_to_attribute(mi, cpb)
                                 else:
                                     newmi = mi

src/calibre/library/save_to_disk.py

@@ -281,7 +281,7 @@ def save_book_to_disk(id, db, root, opts, length):
             stream.seek(0)
             try:
                 if cpb:
-                    newmi = mi.deepcopy()
+                    newmi = mi.deepcopy_metadata()
                     newmi.template_to_attribute(mi, cpb)
                 else:
                     newmi = mi