From 3dc414981e662ac1413d4edec477281cdce97d6f Mon Sep 17 00:00:00 2001
From: "Maxim.Mossienko" <Maxim.Mossienko@jetbrains.com>
Date: Sat, 12 Mar 2016 16:57:00 +0100
Subject: [PATCH] treat second and subsequent occurrence calls for the same
 value as no op (to avoid (de)serialization problems for duplicates like
 WEB-20651)

---
 .../core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java  | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java b/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
index 749d96344473..61d7d8b061cc 100644
--- a/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
+++ b/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
@@ -124,6 +124,10 @@ public class ObjectStubTree<T extends Stub> {
       } else {
         int lastZero;
         for(lastZero = list.length - 1; lastZero >=0 && list[lastZero] == 0; --lastZero);
+        if (list[lastZero] == myStubIdx) {
+          // second and subsequent occurrence calls for the same value are no op
+          return;
+        }
         ++lastZero;
 
         if (lastZero == list.length) {