.

wcfs/internal/xbtree/δbtail.go

@@ -574,7 +574,9 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
 			if err != nil {
 				return ΔB{}, err
 			}
-			// XXX assert δTtail.trackNew.Empty()
+			if !δTtail.trackNew.Empty() {
+				panicf("BUG: ΔBtail.Update: ΔTtail<%s>.trackNew != ø after _Update1", root)
+			}
 			δTtail.trackNew = trackNew
 
 			// XXX vvv we can skip computing diff for HEAD~..HEAD (we just