Fix issues noted during MicroPython v1.19.1 merge.

gather is now async, and the one `yield` that was in it was replaced by `await core._never()`.

Incorporated adafruit/circuitpython@55169e0#diff-01b6761622028d47c6d1c2293fa365de3d8f03feb485d42e42ea9050198e1635 which never got into the asyncio library previously. (I fixed the bug independently, but didn't understand why it was needed, until I found that PR.)

Author: dhalbert

asyncio/funcs.py

@@ -59,7 +59,7 @@ async def wait_for(aw, timeout, sleep=core.sleep):
         # Wait for the timeout to elapse.
         await sleep(timeout)
     except core.CancelledError as er:
-        status = er.value
+        status = er.args[0] if er.args else None
         if status is None:
             # This wait_for was cancelled externally, so cancel aw and re-raise.
             runner_task.cancel()
@@ -92,7 +92,7 @@ def remove(t):
         pass
 
 
-def gather(*aws, return_exceptions=False):
+async def gather(*aws, return_exceptions=False):
     """Run all *aws* awaitables concurrently. Any *aws* that are not tasks
     are promoted to tasks.
 
@@ -134,7 +134,7 @@ def done(t, er):
     # Wait for the a sub-task to need attention.
     gather_task.data = _Remove
     try:
-        yield
+        await core._never()
     except core.CancelledError as er:
         cancel_all = True
         state = er

asyncio/task.py

@@ -167,8 +167,12 @@ def __iter__(self):
 
     def __next__(self):
         if not self.state:
-            # Task finished, raise return value to caller so it can continue.
-            raise self.data
+            if self.data is None:
+                # Task finished but has already been sent to the loop's exception handler.
+                raise StopIteration
+            else:
+                # Task finished, raise return value to caller so it can continue.
+                raise self.data
         else:
             # Put calling task on waiting queue.
             self.state.push(core.cur_task)