fix Storm_Model_Abstract::hasChange() bug

tests/Storm/Test/AttributeChangeTest.php

@@ -122,6 +122,11 @@ class Storm_Test_AttributeChangeForExistingUserTest extends Storm_Test_ModelTest
   function nullAttributeShouldNotHaveChanged(){
     $this->assertFalse($this->user->hasChangedAttribute(null));
   }
+
+  /** @test */
+  public function modelShouldHaveChange() {
+    $this->assertTrue($this->user->hasChange());
+  }
 }
 
 ?>
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