Scenario (prior this change):
A task in lnpeer.Peer.taskgroup raises ORIG_EXC, e.g. in htlc_switch.
The taskgroup then cancels all its tasks and then awaits each (in cancel_remaining):
https://github.com/kyuupichan/aiorpcX/blob/4e64c560422b1fc1dcebc2f926f4b74894e34cdf/aiorpcx/curio.py#L217-L221
In Peer.main_loop, we would want ORIG_EXC to be raised,
but instead LightningPeerConnectionClosed() will be raised as
the Peer._message_loop() task is cancelled, and it is awaited first in cancel_remaining.
We should make sure that if a task is cancelled it will let the CancelledError
propagate out, or at least it does not raise a different exception instead.
SomberNight
fa1762792a