[IMP] testing: avoid error on test failure / abort

It's not entirely clear but I assume if / when a test fails or is
aborted (via C-c) pytest kills the stdout somehow. Either way this
causes a bunch of `OSError` to be logged out as we try to write to
closed pipes.

If that occurs, assume the test is gone and just bail out of the
thread.

conftest.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import datetime
+import errno
 import select
 import shutil
 import threading
@@ -515,7 +516,12 @@ def server(request, db, port, module, addons_path, tmpdir):
                 r = os.read(inpt, 4096)
                 if not r:
                     break
-                os.write(output, r)
+                try:
+                    os.write(output, r)
+                except OSError as e:
+                    if e.errno == errno.EBADF:
+                        break
+                    raise
                 buf.extend(r)
         os.close(inpt)