GH-124639: add back loop param to staggered_race

Lib/asyncio/staggered.py

@@ -11,7 +11,7 @@
 class _Done(Exception):
     pass
 
-async def staggered_race(coro_fns, delay):
+async def staggered_race(coro_fns, delay, *, loop=None):
     """Run coroutines with staggered start times and take the first to finish.
 
     This method takes an iterable of coroutine functions. The first one is
@@ -82,7 +82,13 @@ async def run_one_coro(this_index, coro_fn, this_failed):
             raise _Done
 
     try:
-        async with taskgroups.TaskGroup() as tg:
+        tg = taskgroups.TaskGroup()
+        # Intentionally override the loop in the TaskGroup to avoid
+        # using the running loop, preserving backwards compatibility
+        # TaskGroup only starts using `_loop` after `__aenter__`
+        # so overriding it here is safe.
+        tg._loop = loop
+        async with tg:
             for this_index, coro_fn in enumerate(coro_fns):
                 this_failed = locks.Event()
                 exceptions.append(None)