wcfs: applying Kirills suggestions for improved debug log

wcfs/wcfs.go

@@ -909,7 +909,7 @@ retry:
 
 	if log.V(2) {
 		// debug dump δF
-		log.Infof("\n\nS: handleδZ: δF (#%d):\n", len(δF.ByFile))
+		log.Infof("\n\nS: >>> handleδZ: δF (#%d):\n", len(δF.ByFile))
 		for foid, δfile := range δF.ByFile {
 			blkv := δfile.Blocks.Elements()
 			sort.Slice(blkv, func(i, j int) bool {
@@ -925,6 +925,8 @@ retry:
 			log.Infof("S: \t- %s\t%2s %v\n", foid, flags, blkv)
 		}
 		log.Infof("\n\n")
+
+		defer log.Infof("\n\nS: <<< handleδZ\n")
 	}
 
 	// put zhead's transaction into ctx because we will potentially need to