Move ETag/snapshot computation into a pre-commit try/except OSError so
read errors still convert to a clean 500 before any status line is sent.
Remove the outer OSError catch around body transmission: once
end_headers() returns the response is committed, and a client disconnect
(BrokenPipeError et al.) during the snapshot write or fdopen stream would
previously have triggered bad() -> send_response(500) as a second status
line on a dead stream. Body paths now catch _CLIENT_DISCONNECT_ERRORS
(same tuple as _safe_write()), log at debug, and return True.
Add regression tests with a fake writer that raises BrokenPipeError
after end_headers() for both body paths, asserting exactly one
send_response call.
happy5318
1ff002d170