pyproject.toml

chg: ignore already closed fds when cleaning up

This should fix this error we see in the CI from time to time:

```
--- /tmp/mercurial-ci/tests/test-chg.t
+++ /tmp/mercurial-ci/tests/test-chg.t.err
@@ -187,6 +187,26 @@
   $ chg bulkwrite --pager=on --color no --config ui.formatted=True
   paged! 'going to write massive data\n'
   killed! (?)
+  Traceback (most recent call last):
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/commandserver.py", line 509, in _serverequest
+      sv.cleanup()
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/chgserver.py", line 382, in cleanup
+      self._restoreio()
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/chgserver.py", line 461, in _restoreio
+      os.close(fd)
+  OSError: [Errno 9] Bad file descriptor
+  Traceback (most recent call last):
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/commandserver.py", line 693, in _acceptnewconnection
+      self._runworker(conn)
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/commandserver.py", line 744, in _runworker
+      prereposetups=[self._reposetup],
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/commandserver.py", line 509, in _serverequest
+      sv.cleanup()
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/chgserver.py", line 382, in cleanup
+      self._restoreio()
+    File "/tmp/hgtests._uvojvqb/install/lib/python/mercurial/chgserver.py", line 461, in _restoreio
+      os.close(fd)
+  OSError: [Errno 9] Bad file descriptor
   [255]
```

[build-system]
requires = ["setuptools", "wheel"]

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true