Reduce "ignore cases" script to `trio`-only

Remove all the `tractor` usage (with IPC ctxs) and just get us
a min-reproducing-example with a multi-task-single `trio.Lock`.
The wrapping test suite runs the exact same with an ignore case and
an `.xfail()` for when we let the `trio.WouldBlock` be unmasked.

examples/trio/lockacquire_not_unmasked.py

@@ -1,3 +1,6 @@
+from contextlib import (
+    asynccontextmanager as acm,
+)
 from functools import partial
 
 import tractor
@@ -8,87 +11,72 @@ log = tractor.log.get_logger(
     name=__name__
 )
 
+_lock: trio.Lock|None = None
 
+
+@acm
 async def acquire_singleton_lock(
-    _lock = trio.Lock(),
 ) -> None:
+    global _lock
+    if _lock is None:
+        log.info('Allocating LOCK')
+        _lock = trio.Lock()
+
     log.info('TRYING TO LOCK ACQUIRE')
-    await _lock.acquire()
-    log.info('ACQUIRED')
+    async with _lock:
+        log.info('ACQUIRED')
+        yield _lock
+
+    log.info('RELEASED')
 
 
-@tractor.context
-async def acquire_actor_global_lock(
-    ctx: tractor.Context,
 
-    ignore_special_cases: bool,
+async def hold_lock_forever(
+    task_status=trio.TASK_STATUS_IGNORED
 ):
-    if not ignore_special_cases:
-        from tractor.trionics import _taskc
-        _taskc._mask_cases.clear()
-
-    await acquire_singleton_lock()
-    await ctx.started('locked')
-
-    # block til cancelled
-    await trio.sleep_forever()
+    async with (
+        tractor.trionics.maybe_raise_from_masking_exc(),
+        acquire_singleton_lock() as lock,
+    ):
+        task_status.started(lock)
+        await trio.sleep_forever()
 
 
 async def main(
     ignore_special_cases: bool,
     loglevel: str = 'info',
     debug_mode: bool = True,
-
-    _fail_after: float = 2,
 ):
-    tractor.log.get_console_log(level=loglevel)
+    async with (
+        trio.open_nursery() as tn,
 
-    with trio.fail_after(_fail_after):
-        async with (
-            tractor.trionics.collapse_eg(),
-            tractor.open_nursery(
-                debug_mode=debug_mode,
-                loglevel=loglevel,
-            ) as an,
-            trio.open_nursery() as tn,
-        ):
-            ptl = await an.start_actor(
-                'locker',
-                enable_modules=[__name__],
+        # tractor.trionics.maybe_raise_from_masking_exc()
+        # ^^^ XXX NOTE, interestingly putting the unmasker
+        # here does not exhibit the same behaviour ??
+    ):
+        if not ignore_special_cases:
+            from tractor.trionics import _taskc
+            _taskc._mask_cases.clear()
+
+        _lock = await tn.start(
+            hold_lock_forever,
+        )
+        with trio.move_on_after(0.2):
+            await tn.start(
+                hold_lock_forever,
             )
 
-            async def _open_ctx(
-                task_status=trio.TASK_STATUS_IGNORED,
-            ):
-                async with ptl.open_context(
-                    acquire_actor_global_lock,
-                    ignore_special_cases=ignore_special_cases,
-                ) as pair:
-                    task_status.started(pair)
-                    await trio.sleep_forever()
-
-            first_ctx, first = await tn.start(_open_ctx,)
-            assert first == 'locked'
-
-            with trio.move_on_after(0.5):# as cs:
-                await _open_ctx()
-
-            # await tractor.pause()
-            print('cancelling first IPC ctx!')
-            await first_ctx.cancel()
-
-            await ptl.cancel_actor()
-            # await tractor.pause()
+        tn.cancel_scope.cancel()
 
 
 # XXX, manual test as script
 if __name__ == '__main__':
     tractor.log.get_console_log(level='info')
-    for case in [False, True]:
+    for case in [True, False]:
         log.info(
             f'\n'
             f'------ RUNNING SCRIPT TRIAL ------\n'
-            f'child_errors_midstream: {case!r}\n'
+            f'ignore_special_cases: {case!r}\n'
         )
         trio.run(partial(
             main,