net/http: TestNoSniffExpectRequestBody_h2 failures with "NO_ERROR"

[bcmills]

greplogs --dashboard -md -l -e 'FAIL: TestNoSniffExpectRequestBody_h2'

2021-11-22T19:43:16-8f559bc/linux-386-stretch
2021-11-14T17:38:42-5337e53/openbsd-386-68
2021-10-15T20:34:15-1b072b3/freebsd-arm-paulzhol
2021-10-13T04:00:15-e8f99da/dragonfly-amd64
Note: 1-year break here!
2020-10-30T16:27:42-676ad56/solaris-amd64-oraclerel
2020-10-30T00:47:37-e62adb1/aix-ppc64
2020-10-30T00:23:50-faa4426/aix-ppc64
2020-10-30T00:13:25-60f42ea/solaris-amd64-oraclerel

It's not obvious to me, but given the similarity of the failure mode I suspect that perhaps bundling in the fix for #49645 will also fix this..?

CC @neild

[bcmills]

(Marking as release-blocker for 1.18 because the 1-year gap in failures makes me suspect a 1.18 regression.)

[heschi]

Do we think this should block the beta?