make tx.deserialize preserve existing inputs

gui/qt/transaction_dialog.py

@@ -45,7 +45,7 @@ class TxDialog(QWidget):
         Pass desc to give a description for txs not yet in the wallet.
         '''
         self.tx = tx
-        tx_dict = tx.as_dict()
+        self.tx.deserialize()
         self.parent = parent
         self.wallet = parent.wallet
         self.prompt_if_unsaved = prompt_if_unsaved

lib/transaction.py

@@ -482,6 +482,7 @@ class Transaction:
 
     def __init__(self, raw):
         self.raw = raw
+        self.inputs = None
 
     def update(self, raw):
         self.raw = raw
@@ -518,6 +519,8 @@ class Transaction:
 
 
     def deserialize(self):
+        if self.inputs is not None:
+            return
         d = deserialize(self.raw)
         self.inputs = d['inputs']
         self.outputs = [(x['type'], x['address'], x['value']) for x in d['outputs']]