[catoc]

The stack exchange article seems to ascribe the risk to using MD5. While adding a (global or appended data) hash as you suggest cannot hurt, I wonder if the suggested weakness exist for sha-512.

[timo_h]

The same principle applies to SHA-512 just the same (much cheaper to attack non-stretched SHA-512 hash than attacking directly the bcrypt hash).

There are both MD5 hashes and SHA-512 hashes lying around, which makes "hash shucking" possible for both of them.