diff --git a/maven-project/src/main/java/org/apache/maven/project/ModelUtils.java b/maven-project/src/main/java/org/apache/maven/project/ModelUtils.java
index 66527df427..7e6de40f6a 100644
--- a/maven-project/src/main/java/org/apache/maven/project/ModelUtils.java
+++ b/maven-project/src/main/java/org/apache/maven/project/ModelUtils.java
@@ -82,6 +82,11 @@ public final class ModelUtils
 
                 String parentInherited = parentPlugin.getInherited();
 
+                // only merge plugin definition from the parent if at least one 
+                // of these is true:
+                // 1. we're not processing the plugins in an inheritance-based merge
+                // 2. the parent's <inherited/> flag is not set
+                // 3. the parent's <inherited/> flag is set to true
                 if ( !handleAsInheritance || parentInherited == null ||
                     Boolean.valueOf( parentInherited ).booleanValue() )
                 {
@@ -97,18 +102,21 @@ public final class ModelUtils
                         mergePluginDefinitions( childPlugin, parentPlugin, handleAsInheritance );
                     }
 
+                    // if we're processing this as an inheritance-based merge, and
+                    // the parent's <inherited/> flag is not set, then we need to
+                    // clear the inherited flag in the merge result.
                     if ( handleAsInheritance && parentInherited == null )
                     {
                         assembledPlugin.unsetInheritanceApplied();
                     }
 
                     mergedPlugins.add(assembledPlugin);
+
+                    // fix for MNG-2221 (assembly cache was not being populated for later reference):
+                    assembledPlugins.put(  assembledPlugin.getKey(), assembledPlugin );
                 }
             }
 
-	    // FIXME: not sure what's intended here, but this entire
-	    // loop can be replaced by 'mergedPlugins.addAll( childPlugins.values() );
-	    // since assembledPlugins is never updated and remains empty.
             for ( Iterator it = childPlugins.values().iterator(); it.hasNext(); )
             {
                 Plugin childPlugin = (Plugin) it.next();
diff --git a/maven-project/src/test/java/org/apache/maven/project/ModelUtilsTest.java b/maven-project/src/test/java/org/apache/maven/project/ModelUtilsTest.java
index 60a6a98e92..eb4525196e 100644
--- a/maven-project/src/test/java/org/apache/maven/project/ModelUtilsTest.java
+++ b/maven-project/src/test/java/org/apache/maven/project/ModelUtilsTest.java
@@ -2,12 +2,14 @@ package org.apache.maven.project;
 
 import junit.framework.TestCase;
 
+import org.apache.maven.model.Build;
 import org.apache.maven.model.Plugin;
 import org.apache.maven.model.PluginContainer;
 import org.apache.maven.model.PluginExecution;
 import org.apache.maven.model.Dependency;
 
 import java.util.Collections;
+import java.util.List;
 
 /*
  * Copyright 2001-2005 The Apache Software Foundation.
@@ -77,6 +79,80 @@ public class ModelUtilsTest
         assertEquals( 2, child.getExecutions().size() );
     }
 
+    public void testShouldMergeOnePluginWithInheritExecutionWithoutDuplicatingPluginInList()
+    {
+        Plugin parent = new Plugin();
+        parent.setArtifactId( "testArtifact" );
+        parent.setGroupId( "testGroup" );
+        parent.setVersion( "1.0" );
+
+        PluginExecution parentExecution = new PluginExecution();
+        parentExecution.setId( "testExecution" );
+
+        parent.addExecution( parentExecution );
+        
+        Build parentContainer = new Build();
+        parentContainer.addPlugin( parent );
+
+        Plugin child = new Plugin();
+        child.setArtifactId( "testArtifact" );
+        child.setGroupId( "testGroup" );
+        child.setVersion( "1.0" );
+        
+        Build childContainer = new Build();
+        childContainer.addPlugin( child );
+
+        ModelUtils.mergePluginLists( childContainer, parentContainer, true );
+        
+        List plugins = childContainer.getPlugins();
+        
+        assertEquals( 1, plugins.size() );
+        
+        Plugin plugin = (Plugin) plugins.get( 0 );
+        
+        assertEquals( 1, plugin.getExecutions().size() );
+    }
+
+    public void testShouldMergePluginWithDifferentExecutionFromParentWithoutDuplicatingPluginInList()
+    {
+        Plugin parent = new Plugin();
+        parent.setArtifactId( "testArtifact" );
+        parent.setGroupId( "testGroup" );
+        parent.setVersion( "1.0" );
+
+        PluginExecution parentExecution = new PluginExecution();
+        parentExecution.setId( "testExecution" );
+
+        parent.addExecution( parentExecution );
+        
+        Build parentContainer = new Build();
+        parentContainer.addPlugin( parent );
+
+        Plugin child = new Plugin();
+        child.setArtifactId( "testArtifact" );
+        child.setGroupId( "testGroup" );
+        child.setVersion( "1.0" );
+
+        PluginExecution childExecution = new PluginExecution();
+        childExecution.setId( "testExecution2" );
+
+        child.addExecution( childExecution );
+
+        
+        Build childContainer = new Build();
+        childContainer.addPlugin( child );
+
+        ModelUtils.mergePluginLists( childContainer, parentContainer, true );
+        
+        List plugins = childContainer.getPlugins();
+        
+        assertEquals( 1, plugins.size() );
+        
+        Plugin plugin = (Plugin) plugins.get( 0 );
+        
+        assertEquals( 2, plugin.getExecutions().size() );
+    }
+
     public void testShouldNOTMergeInheritedPluginHavingInheritEqualFalse()
     {
         Plugin parent = new Plugin();