Fix a bug that prevented the blockchain to sync

Blocks with reveal transactions that were loaded from disk could not be
distributed to other nodes before. This prevented new nodes with an old
blockchain state from synchronizing the blockchain.

This bug has now been fixed.

blockchain.py

@@ -515,6 +515,7 @@ class Blockchain:
                     block_obj = self.add_block(block, associated_data)
                     if not block_obj.validate(self):
                         break
+                    self.cache_associated_data(block_obj.transaction)
                     last_valid = block_obj
         except FileNotFoundError:
             pass