The renewal loop re-posted the challenge every time it polled and found the
authorization still pending. RFC 8555 section 7.5.1 has the client post a
challenge once to say it is ready and then poll; a server that has already
moved the challenge to "processing" refuses a second post, and pebble
answers 400 malformed, which failed the whole renewal.
Verified against pebble: the 400s are gone and the client polls. The suite
still can't finish on this machine, because pebble never reaches the test
server to validate the challenge; that path is the environment, and the
runbook now says so.
`cargo test -p tests` runs none of the fork's own feature suites except
what's inside `system_tests`: SCIM, per-domain directories, the sharded
stores and the four replica suites are all ignored, each needing a
container, a STORE the harness only builds on request, or both. The
runbook lists what each one needs, and the container-reuse trap.
jcoffey-dev