kivy: fix is_exit behaviour

gui/kivy/main_window.py

@@ -447,7 +447,6 @@ class ElectrumWindow(App):
             self.is_exit = True
             self.show_info(_('Press again to exit'))
             return True
-        self.is_exit = False
         # override settings button
         if key in (319, 282): #f1/settings button on android
             #self.gui.main_gui.toggle_settings(self)

gui/kivy/uix/dialogs/__init__.py

@@ -182,6 +182,9 @@ class InfoBubble(Factory.Bubble):
                 App.get_running_app().stop()
                 import sys
                 sys.exit()
+            else:
+                App.get_running_app().is_exit = False
+
         if now:
             return on_stop()