Fix Py37 deprecation warning regarding asyncio.Task.current_task()

Author: 1st1

asyncpg/compat.py

@@ -5,6 +5,7 @@
 # the Apache 2.0 License: http://www.apache.org/licenses/LICENSE-2.0
 
 
+import asyncio
 import functools
 import os
 import pathlib
@@ -13,6 +14,7 @@
 
 
 PY_36 = sys.version_info >= (3, 6)
+PY_37 = sys.version_info >= (3, 7)
 SYSTEM = platform.uname().system
 
 
@@ -69,3 +71,11 @@ def get_pg_home_directory() -> pathlib.Path:
 else:
     def get_pg_home_directory() -> pathlib.Path:
         return pathlib.Path.home()
+
+
+if PY_37:
+    def current_asyncio_task(loop):
+        return asyncio.current_task(loop)
+else:
+    def current_asyncio_task(loop):
+        return asyncio.Task.current_task(loop)

asyncpg/connection.py

@@ -1159,7 +1159,7 @@ async def _cancel(self, waiter):
                 waiter.set_exception(ex)
         finally:
             self._cancellations.discard(
-                asyncio.Task.current_task(self._loop))
+                compat.current_asyncio_task(self._loop))
             if not waiter.done():
                 waiter.set_result(None)
             if w is not None: