With <mover>, minsize of U+2192 is not respected when base is one letter

In

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mover>
    <mi>x</mi>
    <mo minsize="3em" stretchy="true">&#x2192;</mo>
  </mover>
</math>

the output produces the small vector arrow, while

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mover>
    <mi>xx</mi>
    <mo minsize="3em" stretchy="true">&#x2192;</mo>
  </mover>
</math>

the arrow is properly stretched. This is probably due to the accent translation used for single letters that converts U+2192 to U+20D7, with U+20D7 no having stretchy data. Adding U+20D7 as an alias to U+2192 for stretchy data should do the trick.