diff -r 22517d09657b -r 8645577fd2c5 lucene/src/java/org/apache/lucene/index/IndexWriter.java
--- a/lucene/src/java/org/apache/lucene/index/IndexWriter.java	Wed Sep 08 10:33:38 2010 +0000
+++ b/lucene/src/java/org/apache/lucene/index/IndexWriter.java	Wed Sep 08 06:36:22 2010 -0400
@@ -4542,6 +4542,10 @@
       // if any structural changes (new segments), we are
       // stale
       return false;
+    } else if (infos.getGeneration() != segmentInfos.getGeneration()) {
+      // if any commit took place since we were opened, we
+      // are stale
+      return false;
     } else {
       return !docWriter.anyChanges();
     }
diff -r 22517d09657b -r 8645577fd2c5 lucene/src/test/org/apache/lucene/index/RandomIndexWriter.java
--- a/lucene/src/test/org/apache/lucene/index/RandomIndexWriter.java	Wed Sep 08 10:33:38 2010 +0000
+++ b/lucene/src/test/org/apache/lucene/index/RandomIndexWriter.java	Wed Sep 08 06:36:22 2010 -0400
@@ -110,10 +110,18 @@
     w.commit();
   }
   
+  public int numDocs() throws IOException {
+    return w.numDocs();
+  }
+
   public int maxDoc() {
     return w.maxDoc();
   }
 
+  public void deleteAll() throws IOException {
+    w.deleteAll();
+  }
+
   public IndexReader getReader() throws IOException {
     // If we are writing with PreFlexRW, force a full
     // IndexReader.open so terms are sorted in codepoint
diff -r 22517d09657b -r 8645577fd2c5 lucene/src/test/org/apache/lucene/index/TestIndexWriterReader.java
--- a/lucene/src/test/org/apache/lucene/index/TestIndexWriterReader.java	Wed Sep 08 10:33:38 2010 +0000
+++ b/lucene/src/test/org/apache/lucene/index/TestIndexWriterReader.java	Wed Sep 08 06:36:22 2010 -0400
@@ -156,7 +156,7 @@
     assertTrue(r1.isCurrent());
 
     writer.commit();
-    assertTrue(r1.isCurrent());
+    assertFalse(r1.isCurrent());
 
     assertEquals(200, r1.maxDoc());
 
@@ -725,12 +725,12 @@
             final Random r = new Random();
             do {
               try {
-                for(int i=0;i<10;i++) {
-                  writer.addDocument(createDocument(10*count+i, "test", 4));
+                for(int docUpto=0;docUpto<10;docUpto++) {
+                  writer.addDocument(createDocument(10*count+docUpto, "test", 4));
                 }
                 count++;
                 final int limit = count*10;
-                for(int i=0;i<5;i++) {
+                for(int delUpto=0;delUpto<5;delUpto++) {
                   int x = r.nextInt(limit);
                   writer.deleteDocuments(new Term("field3", "b"+x));
                 }
diff -r 22517d09657b -r 8645577fd2c5 lucene/src/test/org/apache/lucene/index/TestIsCurrent.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lucene/src/test/org/apache/lucene/index/TestIsCurrent.java	Wed Sep 08 06:36:22 2010 -0400
@@ -0,0 +1,118 @@
+package org.apache.lucene.index;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.Field.Index;
+import org.apache.lucene.document.Field.Store;
+import org.apache.lucene.util.*;
+import org.apache.lucene.analysis.*;
+import org.apache.lucene.store.*;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.Random;
+
+public class TestIsCurrent extends LuceneTestCaseJ4 {
+
+  private RandomIndexWriter writer;
+
+  private Directory directory;
+
+  private Random rand;
+
+  @Override
+  public void setUp() throws Exception {
+    super.setUp();
+
+    rand = newRandom();
+
+    // initialize directory
+    directory = newDirectory(rand);
+    writer = new RandomIndexWriter(rand, directory);
+
+    // write document
+    Document doc = new Document();
+    doc.add(new Field("UUID", "1", Store.YES, Index.ANALYZED));
+    writer.addDocument(doc);
+    writer.commit();
+  }
+
+  @Override
+  public void tearDown() throws Exception {
+    super.tearDown();
+    writer.close();
+    directory.close();
+  }
+
+  /**
+   * Failing testcase showing the trouble
+   * 
+   * @throws IOException
+   */
+  @Test
+  public void testDeleteByTermIsCurrent() throws IOException {
+
+    // get reader
+    IndexReader reader = writer.getReader();
+
+    // assert index has a document and reader is up2date 
+    assertEquals("One document should be in the index", 1, writer.numDocs());
+    assertTrue("Document added, reader should be stale ", reader.isCurrent());
+
+    // remove document
+    Term idTerm = new Term("UUID", "1");
+    writer.deleteDocuments(idTerm);
+    writer.commit();
+
+    // assert document has been deleted (index changed), reader is stale
+    assertEquals("Document should be removed", 0, writer.numDocs());
+    assertFalse("Reader should be stale", reader.isCurrent());
+
+    reader.close();
+  }
+
+  /**
+   * Testcase for example to show that writer.deleteAll() is working as expected
+   * 
+   * @throws IOException
+   */
+  @Test
+  public void testDeleteAllIsCurrent() throws IOException {
+
+    // get reader
+    IndexReader reader = writer.getReader();
+
+    // assert index has a document and reader is up2date 
+    assertEquals("One document should be in the index", 1, writer.numDocs());
+    assertTrue("Document added, reader should be stale ", reader.isCurrent());
+
+    // remove all documents
+    writer.deleteAll();
+    writer.commit();
+
+    // assert document has been deleted (index changed), reader is stale
+    assertEquals("Document should be removed", 0, writer.numDocs());
+    assertFalse("Reader should be stale", reader.isCurrent());
+
+    reader.close();
+  }
+}