[3.9] bpo-45097: Remove incorrect deprecation warnings in asyncio. (GH-28153)

Deprecation warnings about the loop argument were incorrectly emitted
in cases when the loop argument was used inside the asyncio library,
not from user code.

Lib/asyncio/tasks.py

@@ -580,15 +580,16 @@ def as_completed(fs, *, loop=None, timeout=None):
     if futures.isfuture(fs) or coroutines.iscoroutine(fs):
         raise TypeError(f"expect an iterable of futures, not {type(fs).__name__}")
 
+    if loop is not None:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
+
     from .queues import Queue  # Import here to avoid circular import problem.
     done = Queue(loop=loop)
 
     if loop is None:
         loop = events.get_event_loop()
-    else:
-        warnings.warn("The loop argument is deprecated since Python 3.8, "
-                      "and scheduled for removal in Python 3.10.",
-                      DeprecationWarning, stacklevel=2)
     todo = {ensure_future(f, loop=loop) for f in set(fs)}
     timeout_handle = None
 
@@ -756,6 +757,10 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
                       "and scheduled for removal in Python 3.10.",
                       DeprecationWarning, stacklevel=2)
 
+    return _gather(*coros_or_futures, loop=loop, return_exceptions=return_exceptions)
+
+
+def _gather(*coros_or_futures, loop=None, return_exceptions=False):
     if not coros_or_futures:
         if loop is None:
             loop = events.get_event_loop()