Changes with nginx 1.21.1
*) Change: now nginx always returns an error for the CONNECT method.
*) Change: now nginx always returns an error if both "Content-Length"
and "Transfer-Encoding" header lines are present in the request.
*) Change: now nginx always returns an error if spaces or control
characters are used in the request line.
*) Change: now nginx always returns an error if spaces or control
characters are used in a header name.
*) Change: now nginx always returns an error if spaces or control
characters are used in the "Host" request header line.
*) Change: optimization of configuration testing when using many
listening sockets.
*) Bugfix: nginx did not escape """, "<", ">", "\", "^", "`", "{", "|",
and "}" characters when proxying with changed URI.
*) Bugfix: SSL variables might be empty when used in logs; the bug had
appeared in 1.19.5.
*) Bugfix: keepalive connections with gRPC backends might not be closed
after receiving a GOAWAY frame.
*) Bugfix: reduced memory consumption for long-lived requests when
proxying with more than 64 buffers.
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