Crucial to functioning replication is deterministic revisions. Attachment md5 sums are used in CouchDB's revision generation (see couch_db:new_revid/1).
Alternative CouchDB implementations may find it impossible or impractical to support binary attachments yet still wish to track changes and replicate efficiently with Apache CouchDB. To this end, such implementations need an efficient way to fetch all metadata necessary for calculating compatible revisions in the event of locally executed future updates.
As a bonus, exposing this metadata is particularly beneficial for filesystem sync tools (such as couchapp implementations), e.g. through eliminating the need for redundantly storing checksums as user data on synchronized documents.
To this end I propose the following 5-line patch which applies cleanly to trunk, 1.1.x and 1.0.x.