In short, the prior code was far too simplistic when it came to calling recv(2)
and failed intermittently (or in the case of Jenkins, deterministically).
Handle short recv(2)s by checking the return code and incrementing the window
into the buffer by the number of received bytes. If the number of received
bytes <= 0, then bail out and test the total number of received bytes vs the
expected number of bytes sent for equality and base whether or not the test
passes/fails on that fact.
Remove the expected failure, now that the testcase deterministically
passes [1].
PR: 234809 [1], 235200
MFC after: 1 week