File "Electrum-3.1.1-py3.6.egg/electrum_gui/qt/main_window.py", line 2892, in on_currency
  File "Electrum-3.1.1-py3.6.egg/electrum/exchange_rate.py", line 466, in set_enabled
  File "Electrum-3.1.1-py3.6.egg/electrum/simple_config.py", line 140, in set_key
  File "Electrum-3.1.1-py3.6.egg/electrum/simple_config.py", line 149, in _set_key_in_user_config
  File "Electrum-3.1.1-py3.6.egg/electrum/simple_config.py", line 215, in save_user_config