I have a problem with jquery version 2.1.1

I have a select like this

<select id="test">

   <option value="10">10</option>

   <option value="20" selected="selected">20</option>

   <option value="30">30</option>

   <option value="40">40</option>

</select>

and when I try with chrome  Versión    49.0.262

$('#test option[value="30"]').attr("selected","selected"); 

and after that 

$('#test option:selected'); this return  '<option value="20" selected="selected">20</option>';

but in the Versión 37.0.2062.94 (64-bit) of chrome 

this return '<option value="30">30</option>'

I have same problem with firefox 45.0.

I tried it in javascript console  from the two versions. 

Please anyone has any idea of the problem.

regards