@nicolas-grekas what about my suggestion in #37666 (comment) ?

Here are some examples if we concat both messages:

• "Couldn't resolve host name: Could not resolve host: bad.host.test for "http://bad.host.test/"."
• "Transferred a partial file: transfer closed with 718 bytes remaining to read for "http://localhost:8057/length-broken"."
• "Transferred a partial file: transfer closed with outstanding read data remaining for "http://localhost:8057/chunked-broken"."
• "Couldn't resolve host name: Could not resolve host: foo.example. for "http://foo.example./"."
• "Couldn't resolve host name: Could not resolve host: foo.example. for "http://foo.example./"."
• "Operation was aborted by an application callback: Callback aborted for "http://localhost:8057/timeout-body"."
• "Operation was aborted by an application callback: Callback aborted for "http://localhost:8057/timeout-body"."
• "Timeout was reached: Operation timed out after 100 milliseconds with 462 bytes received for "http://localhost:8057/max-duration"."

That's why I didn't do it here as it looks like this would put duplicates in the message...