The sheer magnitude of the delay points toward the August 1 date conflicting with some exec's kid's dance recital more than a major new bug.
An AMD spokesman suggested as much. Or at least a bit of a juggle of dates, maybe to fit in with some vendor's product launch knees-up. Such shenanigans aren't unusual, he suggested.
When we said earlier that it "might slip some more", this is not what we meant, but we would be happy to take the credit anyway.µ