asyncio: pyflakes, remove unused import

tests: Remove unused function; inline another function

Lib/asyncio/base_events.py

@@ -636,7 +636,7 @@ class BaseEventLoop(events.AbstractEventLoop):
 
         try:
             yield from waiter
-        except Exception as exc:
+        except Exception:
             transport.close()
             raise
 

Lib/asyncio/selector_events.py

@@ -10,7 +10,6 @@ import collections
 import errno
 import functools
 import socket
-import sys
 try:
     import ssl
 except ImportError:  # pragma: no cover