Fix morphTo eager loading

src/Illuminate/Database/Eloquent/Builder.php

@@ -710,7 +710,7 @@ public function getRelation($name)
      * @param  string  $relation
      * @return array
      */
-    public function nestedRelations($relation)
+    protected function nestedRelations($relation)
     {
         $nested = [];
 

src/Illuminate/Database/Eloquent/Model.php

@@ -828,11 +828,11 @@ public function morphTo($name = null, $type = null, $id = null)
         list($type, $id) = $this->getMorphs($name, $type, $id);
 
         // If the type value is null it is probably safe to assume we're eager loading
-        // the relationship. When that is the case we will pass in a dummy query as
-        // there are multiple types in the morph and we can't use single queries.
+        // the relationship. In this case we'll just pass in a dummy query where we
+        // need to remove any eager loads that may already be defined on a model.
         if (empty($class = $this->$type)) {
             return new MorphTo(
-                $this->newQuery(), $this, $id, null, $type, $name
+                $this->newQuery()->setEagerLoads([]), $this, $id, null, $type, $name
             );
         }
 

src/Illuminate/Database/Eloquent/Relations/MorphTo.php

@@ -183,11 +183,9 @@ protected function getResultsByType($type)
 
         $key = $instance->getTable().'.'.$instance->getKeyName();
 
-        $eagerLoads = $this->getQuery()->nestedRelations($this->relation);
-
         $query = $this->replayMacros($instance->newQuery())
             ->mergeModelDefinedRelationConstraints($this->getQuery())
-            ->with($eagerLoads);
+            ->with($this->getQuery()->getEagerLoads());
 
         return $query->whereIn($key, $this->gatherKeysByType($type)->all())->get();
     }

tests/Database/DatabaseEloquentPolymorphicIntegrationTest.php

@@ -104,6 +104,18 @@ public function testItLoadsNestedRelationshipsAutomatically()
         $this->assertEquals(TestUser::first(), $like->likeable->owner);
     }
 
+    public function testItLoadsNestedRelationshipsOnDemand()
+    {
+        $this->seedData();
+
+        $like = TestLike::with('likeable.owner')->first();
+
+        $this->assertTrue($like->relationLoaded('likeable'));
+        $this->assertTrue($like->likeable->relationLoaded('owner'));
+
+        $this->assertEquals(TestUser::first(), $like->likeable->owner);
+    }
+
     /**
      * Helpers...
      */