Support for revid in $document

Fetching $document currently gives me:

{"exptime":0,"deleted":false,"CAS":"0x15a2e134821a0000","seqno":"0x000000000000019a","datatype":["json"],"vbucket_uuid":"0x0000aba9c2f43abd","flags":33554432,"value_crc32c":"0x3c565539","value_bytes":9,"last_modified":"1559056036"} 

can revid please be added to this?

Context: the backup/transactions strategy for Mad Hatter is that, on restoring a document that's found to be mid-transaction, the restore process will convert the document to how it was pre-transaction.  This includes resetting the document's metadata - cas & revid. 
So in a transaction, when the user gets a document, I'd like to get the revid at the same time from $document.  And then when that document is updated in the txn, add that revid (and cas) into the transaction metadata.  It's then available to the restore process.

Appreciate it's late in the day, but it would be very helpful to get this change (which seems low impact and low risk?) in a Mad Hatter timeframe, to be able to meet the previously agreed backup plan.