.

wcfs/δbtail.go

@@ -167,6 +167,7 @@ func NewΔBtail(at0 zodb.Tid, db *zodb.DB) *ΔBtail {
 		δZtail:   zodb.NewΔTail(at0),
 		byRoot:   make(map[zodb.Oid]*ΔTtail),
 		trackIdx: make(map[zodb.Oid]SetOid),
+		tkdel:    SetKey{},
 		db:       db,
 	}
 }
@@ -236,6 +237,14 @@ func (δBtail *ΔBtail) Track(key Key, keyPresent bool, path []Node, flags Track
 		δBtail.byRoot[root] = newΔTtail()
 	}
 
+	if !keyPresent {
+		δBtail.tkdel.Add(key)
+	} else {
+		if δBtail.tkdel.Has(key) {
+			panicf("[%v] was previously tracked as ø", key)
+		}
+	}
+
 	// XXX update diff	XXX here? or as separate step?
 	// XXX update lastRevOf
 }