CBG-4832: Handle legacy rev IDs as deltaSrc even when running in HLV mode (#7698)

Co-authored-by: Tor Colvin <tor.colvin@couchbase.com>

Author: bbrks

db/blip_handler.go

@@ -1141,10 +1141,10 @@ func (bh *blipHandler) processRev(rq *blip.Message, stats *processRevStats) (err
 		//       due to no-conflict write restriction, but we still need to enforce security here to prevent leaking data about previous
 		//       revisions to malicious actors (in the scenario where that user has write but not read access).
 		var deltaSrcRev DocumentRevision
-		if bh.useHLV() {
+		if bh.useHLV() && !base.IsRevTreeID(deltaSrcRevID) {
 			deltaSrcVersion, parseErr := ParseVersion(deltaSrcRevID)
 			if parseErr != nil {
-				return base.HTTPErrorf(http.StatusUnprocessableEntity, "Unable to parse version for delta source for doc %s, error: %v", base.UD(docID), err)
+				return base.HTTPErrorf(http.StatusUnprocessableEntity, "Unable to parse version for delta source for doc %s, error: %v", base.UD(docID), parseErr)
 			}
 			deltaSrcRev, err = bh.collection.GetCV(bh.loggingCtx, docID, &deltaSrcVersion, false)
 		} else {

rest/blip_api_delta_sync_test.go

@@ -933,8 +933,6 @@ func TestBlipDeltaSyncPullRevCache(t *testing.T) {
 // TestBlipDeltaSyncPush tests that a simple push replication handles deltas in EE,
 // and checks that full body replication is still supported in CE.
 func TestBlipDeltaSyncPush(t *testing.T) {
-
-	t.Skip("TODO: CBG-4832 - Failing because of broken legacy rev ID as deltaSrc logic in processRev")
 	base.SetUpTestLogging(t, base.LevelDebug, base.KeyCRUD, base.KeySGTest, base.KeySyncMsg, base.KeySync)
 	sgUseDeltas := base.IsEnterpriseEdition()
 	rtConfig := RestTesterConfig{