Ignore type checking of empty list

This statement is valid; since the list is empty it doesn't really
matter what type of list it is -- update_filesystems is only every
going to try to iterate over it anyway (which will yield no entries).

However, mypy doesn't understand it. Unfortunately I can't find
either a reference to the canonical solution or bug; the nearest
I get is point (8) at python/mypy#1055.

Author: PeterJCLaw

runusb

@@ -260,7 +260,7 @@ def main():
     except KeyboardInterrupt:
         # Tell the registry that all filesystems were unmounted, which has the
         # effect of making it do cleanup.
-        registry.update_filesystems([])
+        registry.update_filesystems([]) # type: ignore
 
 
 if __name__ == '__main__':