[build.webkit.org] Allow users to specify custom revision to checkout for buildbot builds (while building WebKit).
Pull request: https://github.com/WebKit/WebKit/pull/586
Committed r294051 (250457@main): <https://commits.webkit.org/250457@main> Reviewed commits have been landed. Closing PR #586 and removing active labels.
<rdar://problem/93097451>