The patch from Grayson Gordon adds http.sslVerifyStatus. Git currently does not set CURLOPT_SSL_VERIFYSTATUS, so it never requests the TLS Certificate Status Request extension and ignores any stapled OCSP response. The patch description says OpenSSL-linked builds are silent about this, because libcurl installs the status callback only when the option is set.
Junio C Hamano said linux-* CI jobs had been spinning and timing out after six hours for several days. He first bisected between jch and seen, assuming a single topic was to blame, and found that 'seen' with this topic removed did not show the timeouts. He ejected it tentatively, suspecting a possible interaction with other topics.
He then tried the topic in isolation, queued directly on top of Git 2.56. That CI run also timed out many linux-* jobs after six hours, which he said was exactly the breakage he was chasing. The linux-TEST-vars and linux32 jobs also failed, but he said that is unrelated: they cannot download the long-deprecated Ubuntu 20.04, and jobs on other branches often fail the same way.
The excerpts do not show the root cause or a fix. The thread, 40 messages long, also involves Patrick Steinhardt and SZEDER Gábor, and the author has not yet responded in the excerpts.