LGTM.com - false positive for exception handling inside context

**Description of the false positive**

Context Managers can handle and suppress exceptions at the end of their block. A case where

1. an inner exception handler can only be exited with an unhandled exception
2. an outer context manager may recover from an unhandled exception

means the entire block may be exited *without* an active exception. A dangling statement that would not be reachable after 1 alone may be reachable after 1 *and* 2.

**URL to the alert on the project page on LGTM.com**

https://lgtm.com/projects/g/MaineKuehn/usim/snapshot/3d254d3788b0ace175b72abf530fe0d9855fbaa3/files/usim/py/_awaitable.py?sort=name&dir=ASC&mode=heatmap#x20ee98df18122724:1