.

wcfs/internal/zdata/δftail.go

@@ -590,10 +590,13 @@ func (δFtail *ΔFtail) SliceByFileRev(zfile *ZBigFile, lo, hi zodb.Tid) /*reado
 
 		// emit epoch δf
 		if ie >= 0 {
-			δf := vδfTail(vδE[ie].Rev)
-			δf.Epoch = true
-			δf.Blocks = nil // XXX must be already nil
-			δf.Size = false // XXX must be already false
+			epoch := vδE[ie].Rev
+			if epoch > lo { // it could be <=
+				δf := vδfTail(epoch)
+				δf.Epoch = true
+				δf.Blocks = nil // XXX must be already nil
+				δf.Size = false // XXX must be already false
+			}
 		}
 	}