Index: maven-project/src/main/java/org/apache/maven/project/MavenProject.java
===================================================================
--- maven-project/src/main/java/org/apache/maven/project/MavenProject.java	(revision 749018)
+++ maven-project/src/main/java/org/apache/maven/project/MavenProject.java	(working copy)
@@ -1771,17 +1771,17 @@
         {
             String refId = getProjectReferenceId( pluginArtifact.getGroupId(), pluginArtifact.getArtifactId(), pluginArtifact.getVersion() );
             MavenProject ref = (MavenProject) getProjectReferences().get( refId );
-            if ( ref != null && ref.getArtifact() != null )
+            if ( ref != null )
             {
-                // TODO: if not matching, we should get the correct artifact from that project (attached)
-                if ( ref.getArtifact().getDependencyConflictId().equals( pluginArtifact.getDependencyConflictId() ) )
+                if ( ref.getArtifact() != null
+                    && ref.getArtifact().getDependencyConflictId().equals( pluginArtifact.getDependencyConflictId() ) )
                 {
                     // if the project artifact doesn't exist, don't use it. We haven't built that far.
                     if ( ref.getArtifact().getFile() != null && ref.getArtifact().getFile().exists() )
                     {
                         // FIXME: Why aren't we using project.getArtifact() for the second parameter here??
-                        pluginArtifact = new ActiveProjectArtifact( ref, pluginArtifact );
-                        return pluginArtifact;
+                        Artifact resultArtifact = new ActiveProjectArtifact( ref, pluginArtifact );
+                        return resultArtifact;
                     }
                     else
                     {
@@ -1789,31 +1789,90 @@
                     }
                 }
 
-                Iterator itr = ref.getAttachedArtifacts().iterator();
-                while ( itr.hasNext() )
+                Artifact attached = findMatchingArtifact( ref.getAttachedArtifacts(), pluginArtifact );
+                if ( attached != null )
                 {
-                    Artifact attached = (Artifact) itr.next();
-                    if ( attached.getDependencyConflictId().equals( pluginArtifact.getDependencyConflictId() ) )
+                    if ( attached.getFile() != null && attached.getFile().exists() )
                     {
-                        if ( attached.getFile() != null && attached.getFile().exists() )
-                        {
-                            Artifact resultArtifact = ArtifactUtils.copyArtifact( attached );
-                            resultArtifact.setScope( pluginArtifact.getScope() );
-
-                            return resultArtifact;
-                        }
-                        else
-                        {
-                            logMissingSiblingProjectArtifact( pluginArtifact );
-                            break;
-                        }
+                        Artifact resultArtifact = ArtifactUtils.copyArtifact( attached );
+                        resultArtifact.setScope( pluginArtifact.getScope() );
+                        return resultArtifact;
                     }
+                    else
+                    {
+                        logMissingSiblingProjectArtifact( pluginArtifact );
+                    }
                 }
             }
         }
         return pluginArtifact;
     }
-    
+
+    /**
+     * Tries to resolve the specified artifact from the given collection of attached project artifacts.
+     * 
+     * @param artifacts The attached artifacts, may be <code>null</code>.
+     * @param requestedArtifact The artifact to resolve, must not be <code>null</code>.
+     * @return The matching artifact or <code>null</code> if not found.
+     */
+    private Artifact findMatchingArtifact( List artifacts, Artifact requestedArtifact )
+    {
+        if ( artifacts != null && !artifacts.isEmpty() )
+        {
+            // first try matching by dependency conflict id
+            String requestedId = requestedArtifact.getDependencyConflictId();
+            for ( Iterator it = artifacts.iterator(); it.hasNext(); )
+            {
+                Artifact artifact = (Artifact) it.next();
+                if ( requestedId.equals( artifact.getDependencyConflictId() ) )
+                {
+                    return artifact;
+                }
+            }
+
+            // next try matching by repository conflict id
+            requestedId = getRepositoryConflictId( requestedArtifact );
+            for ( Iterator it = artifacts.iterator(); it.hasNext(); )
+            {
+                Artifact artifact = (Artifact) it.next();
+                if ( requestedId.equals( getRepositoryConflictId( artifact ) ) )
+                {
+                    return artifact;
+                }
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Gets the repository conflict id of the specified artifact. Unlike the dependency conflict id, the repository
+     * conflict id uses the artifact file extension instead of the artifact type. Hence, the repository conflict id more
+     * closely reflects the identity of artifacts as perceived by a repository.
+     * 
+     * @param artifact The artifact, must not be <code>null</code>.
+     * @return The repository conflict id, never <code>null</code>.
+     */
+    private String getRepositoryConflictId( Artifact artifact )
+    {
+        StringBuffer buffer = new StringBuffer( 128 );
+        buffer.append( artifact.getGroupId() );
+        buffer.append( ':' ).append( artifact.getArtifactId() );
+        if ( artifact.getArtifactHandler() != null )
+        {
+            buffer.append( ':' ).append( artifact.getArtifactHandler().getExtension() );
+        }
+        else
+        {
+            buffer.append( ':' ).append( artifact.getType() );
+        }
+        if ( artifact.hasClassifier() )
+        {
+            buffer.append( ':' ).append( artifact.getClassifier() );
+        }
+        return buffer.toString();
+    }
+
     private void logMissingSiblingProjectArtifact( Artifact artifact )
     {
         if ( logger == null )