This is not a problem for current API, because it's web context API and we always have one network process per context with a single session. For the new API, we have a global network process with multiple sessions that shouldn't share the allowed certificates.
Pull request: https://github.com/WebKit/WebKit/pull/8874
Committed 259202@main (c02853156a91): <https://commits.webkit.org/259202@main> Reviewed commits have been landed. Closing PR #8874 and removing active labels.