Merge pull request #2946 from ThomasWaldmann/workaround-files-cache-corruption

ignore corrupt files cache, fixes #2939

src/borg/cache.py

@@ -503,10 +503,16 @@ def _read_files(self):
                 if not data:
                     break
                 u.feed(data)
+                try:
                     for path_hash, item in u:
                         entry = FileCacheEntry(*item)
                         # in the end, this takes about 240 Bytes per file
                         self.files[path_hash] = msgpack.packb(entry._replace(age=entry.age + 1))
+                except (TypeError, ValueError) as exc:
+                    logger.warning('The files cache seems corrupt, ignoring it. '
+                                   'Expect lower performance. [%s]' % str(exc))
+                    self.files = {}
+                    return
 
     def begin_txn(self):
         # Initialize transaction snapshot