Otherwise it makes tests potentially flaky as they might try to open a cache that was just being cleaned synchronously.
Created attachment 320584 [details] Patch
Comment on attachment 320584 [details] Patch Clearing flags on attachment: 320584 Committed r221995: <http://trac.webkit.org/changeset/221995>
All reviewed patches have been landed. Closing bug.
<rdar://problem/34693342>