We should adopt webkitcorepy's Python test harness for our buildbot tests because webkitcorepy's test harness is much more ergonomic.
<rdar://problem/111339627>
Pull request: https://github.com/WebKit/WebKit/pull/15298
Committed 267005@main (1eac3c959b1c): <https://commits.webkit.org/267005@main> Reviewed commits have been landed. Closing PR #15298 and removing active labels.
start-local-buildbot-server script has been regressed by this change. See bug#269688.