make flake8 happy, and don't even bother trying to capture from the d…

…evice_changed_to event hook.

udiskie/prompt.py

@@ -237,7 +237,7 @@ async def __call__(self, device, arg1 = None, arg2 = None):
             attrs['event'] = 'device_changed_to'
             argv = [arg.format(**attrs) for arg in self.argv]
             try:
-                stdout2 = await exec_subprocess(argv, self.capture)
+                await exec_subprocess(argv, False)
             except subprocess.CalledProcessError:
                 return None
         return stdout