net/http: TestRequestWriteTransport failures with unexpected Transfer-Encoding in request

[bcmills]

2022/04/26 00:35:58 http: TLS handshake error from 127.0.0.1:38617: EOF
--- FAIL: TestRequestWriteTransport (0.59s)
    requestwrite_test.go:794: test[2]: unexpected Transfer-Encoding in request: GET / HTTP/1.1
        Host: example.com
        User-Agent: Go-http-client/1.1
        Transfer-Encoding: chunked
        Accept-Encoding: gzip
        
        0
        
FAIL
FAIL	net/http	35.584

greplogs --dashboard -md -l -e 'unexpected Transfer-Encoding in request'

2022-04-25T18:06:52-8619d3b/solaris-amd64-oraclerel
2020-01-02T20:13:03-a4c579e/darwin-arm64-mn4m2zdaios

This failure rate is uncommon and has only been observed on non-first-class ports, so leaving on the Backlog for now.

[bcmills]

Expanding the regexp to other failure modes for this test does not reveal any additional failures:

greplogs --dashboard -md -l -e 'FAIL: TestRequestWriteTransport '

2022-04-25T18:06:52-8619d3b/solaris-amd64-oraclerel
2020-01-02T20:13:03-a4c579e/darwin-arm64-mn4m2zdaios

However, it could be that the test is racy in some way; see also #44088.