Update feature_block.py

Author: ComputerCraftr

test/functional/feature_block.py

@@ -160,7 +160,7 @@ def run_test(self):
             blockname = f"for_invalid.{TxTemplate.__name__}"
             self.next_block(blockname)
             badtx = template.get_tx()
-            if TxTemplate != invalid_txs.InputMissing:
+            if TxTemplate != invalid_txs.InputMissing and TxTemplate != invalid_txs.SizeTooSmall:
                 self.sign_tx(badtx, attempt_spend_tx)
             badtx.rehash()
             badblock = self.update_block(blockname, [badtx])