From b4e7ef0ae3878536e39e00504040a88f010268df Mon Sep 17 00:00:00 2001
From: nik <Nikolay.Chashnikov@jetbrains.com>
Date: Wed, 21 Nov 2012 17:32:22 +0400
Subject: [PATCH] optimization [approved by Jeka]

---
 .../src/org/jetbrains/jps/incremental/FSOperations.java         | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/jps/jps-builders/src/org/jetbrains/jps/incremental/FSOperations.java b/jps/jps-builders/src/org/jetbrains/jps/incremental/FSOperations.java
index d37c256e11e1..636c81ff8ea1 100644
--- a/jps/jps-builders/src/org/jetbrains/jps/incremental/FSOperations.java
+++ b/jps/jps-builders/src/org/jetbrains/jps/incremental/FSOperations.java
@@ -176,6 +176,8 @@ public class FSOperations {
   }
 
   public static void pruneEmptyDirs(CompileContext context, @Nullable final Set<File> dirsToDelete) {
+    if (dirsToDelete == null || dirsToDelete.isEmpty()) return;
+
     Set<File> doNotDelete = ALL_OUTPUTS_KEY.get(context);
     if (doNotDelete == null) {
       doNotDelete = new THashSet<File>(FileUtil.FILE_HASHING_STRATEGY);