transaction.py: more flexible sign() method

handles both x_pubkeys and pubkeys in keypairs

lib/wallet.py

@@ -1220,9 +1220,8 @@ class Abstract_Wallet(PrintError):
         if fixed_fee is None and config.fee_per_kb() is None:
             raise NoDynamicFeeEstimates()
 
-        if not is_sweep:
-            for item in inputs:
-                self.add_input_info(item)
+        for item in inputs:
+            self.add_input_info(item)
 
         # change address
         if change_addr: