Update other use of wait_for workaround

Added issue link and comment describing why this workaround
is necessary. Also moved the function to be local to the
call site, as it it not used elsewhere.

Author: aaliddell

asyncpg/connect_utils.py

@@ -615,12 +615,23 @@ async def _connect_addr(*, addr, loop, timeout, params, config,
     else:
         connector = loop.create_connection(proto_factory, *addr)
 
+    def _close_leaked_connection(fut):
+        if not fut.cancelled():
+            tr, pr = fut.result()
+            if tr:
+                tr.close()
+
     connector = asyncio.ensure_future(connector)
     before = time.monotonic()
     try:
         tr, pr = await asyncio.wait_for(
             connector, timeout=timeout)
     except asyncio.CancelledError:
+        # Ensure connection is closed.
+        # The cancellation may have raced the connect, leading
+        # to the connect completing but the wait_for to be
+        # cancelled.
+        # See: https://bugs.python.org/issue37658
         connector.add_done_callback(_close_leaked_connection)
         raise
     timeout -= time.monotonic() - before
@@ -721,12 +732,3 @@ def _create_future(loop):
         return asyncio.Future(loop=loop)
     else:
         return create_future()
-
-
-def _close_leaked_connection(fut):
-    try:
-        tr, pr = fut.result()
-        if tr:
-            tr.close()
-    except asyncio.CancelledError:
-        pass  # hide the exception