dev-python/backoff: new package, add 2.2.1

Upstream is dead. I'll maintain here until dev-util/mock migrates to
another library.

https://github.com/litl/backoff/issues/211

Signed-off-by: Takuya Wakazono <pastalian46@gmail.com>

dev-python/backoff/files/backoff-2.2.1-pytest-asyncio-compat.patch

@@ -0,0 +1,85 @@
+https://github.com/litl/backoff/pull/224
+Adapt test cases to pytest-asyncio 1.0 compatibility
+
+- Remove deprecated event_loop fixture
+  https://pytest-asyncio.readthedocs.io/en/stable/reference/changelog.html#removed
+- Drop *_without_event_loop tests
+  These incompatible tests (*1) are no longer needed since the
+  underlying code has already been removed (introduced in a460156,
+  removed in 5d714ccd).
+
+*1: asyncio.get_event_loop() now raises a RuntimeError in Python 3.14
+    when no loop exists.
+    https://docs.python.org/3.14/whatsnew/3.14.html#id7
+--- a/tests/test_backoff_async.py
++++ b/tests/test_backoff_async.py
+@@ -665,7 +665,7 @@ async def exceptor():
+ 
+ 
+ @pytest.mark.asyncio
+-async def test_on_exception_coro_cancelling(event_loop):
++async def test_on_exception_coro_cancelling():
+     sleep_started_event = asyncio.Event()
+ 
+     @backoff.on_predicate(backoff.expo)
+@@ -679,59 +679,10 @@ async def coro():
+ 
+         return False
+ 
+-    task = event_loop.create_task(coro())
++    task = asyncio.create_task(coro())
+ 
+     await sleep_started_event.wait()
+ 
+     task.cancel()
+ 
+     assert (await task)
+-
+-
+-def test_on_predicate_on_regular_function_without_event_loop(monkeypatch):
+-    monkeypatch.setattr('time.sleep', lambda x: None)
+-
+-    # Set default event loop to None.
+-    loop = asyncio.get_event_loop()
+-    asyncio.set_event_loop(None)
+-
+-    try:
+-        @backoff.on_predicate(backoff.expo)
+-        def return_true(log, n):
+-            val = (len(log) == n - 1)
+-            log.append(val)
+-            return val
+-
+-        log = []
+-        ret = return_true(log, 3)
+-        assert ret is True
+-        assert 3 == len(log)
+-
+-    finally:
+-        # Restore event loop.
+-        asyncio.set_event_loop(loop)
+-
+-
+-def test_on_exception_on_regular_function_without_event_loop(monkeypatch):
+-    monkeypatch.setattr('time.sleep', lambda x: None)
+-
+-    # Set default event loop to None.
+-    loop = asyncio.get_event_loop()
+-    asyncio.set_event_loop(None)
+-
+-    try:
+-        @backoff.on_exception(backoff.expo, KeyError)
+-        def keyerror_then_true(log, n):
+-            if len(log) == n:
+-                return True
+-            e = KeyError()
+-            log.append(e)
+-            raise e
+-
+-        log = []
+-        assert keyerror_then_true(log, 3) is True
+-        assert 3 == len(log)
+-
+-    finally:
+-        # Restore event loop.
+-        asyncio.set_event_loop(loop)