I'm trying to understand this build failure https://dev.azure.com/twistedmatrix/2d0fcc06-a9d2-41d8-86fa-1db3534a2b0c/_ap... the same tree built on Windows OK A typical error is 2021-12-17T05:02:10.2803270Z File "/Users/runner/work/1/s/.tox/alldeps-withcov-posix/lib/python3.7/site-packages/twisted/internet/test/test_unix.py", line 54, in <module> 2021-12-17T05:02:10.2803990Z from twisted.internet.test.test_tcp import ( 2021-12-17T05:02:10.2805100Z File "/Users/runner/work/1/s/.tox/alldeps-withcov-posix/lib/python3.7/site-packages/twisted/internet/test/test_tcp.py", line 128, in <module> 2021-12-17T05:02:10.2806030Z from twisted.internet.test import _posixifaces 2021-12-17T05:02:10.2807270Z File "/Users/runner/work/1/s/.tox/alldeps-withcov-posix/lib/python3.7/site-packages/twisted/internet/test/_posixifaces.py", line 31, in <module> 2021-12-17T05:02:10.2807970Z libc = CDLL(find_library("c") or "") 2021-12-17T05:02:10.2808580Z File "/Users/runner/hostedtoolcache/Python/3.7.12/x64/lib/python3.7/ctypes/__init__.py", line 364, in __init__ 2021-12-17T05:02:10.2809180Z self._handle = _dlopen(self._name, mode) 2021-12-17T05:02:10.2809720Z builtins.OSError: dlopen(, 6): no suitable image found. Did find: 2021-12-17T05:02:10.2810240Z /usr/local/lib/: not a file 2021-12-17T05:02:10.2810650Z /usr/local/lib: not a file 2021-12-17T05:02:10.2811050Z /usr/lib/: not a file 2021-12-17T05:02:10.2811440Z /usr/lib: not a file 2021-12-17T05:02:10.2811670Z 2021-12-17T05:02:10.2812020Z twisted.internet.test.test_unix should this test be running on Mac at all? Ian