Table Properties show invalid value for Headers when header is not the first row in the table

[Jakub Ś]

Steps to reproduce

1. Insert below code into CKEditor

   <table border="1" cellpadding="1" cellspacing="1" dir="ltr" style="width:500px">
   	<thead>
   		<tr>
   			<td>
   			<p>00000</p>
   			<p>11111</p>
   			</td>
   			<td>
   			<p>22222</p>
   			<p>333333</p>
   			</td>
   			<td>
   			<p>444444</p>
   			<p>555555</p>
   			</td>
   		</tr>
   		<tr>
   			<th scope="col">
   			<p>00000</p>
   			<p>11111</p>
   			</th>
   			<th scope="col">
   			<p>22222</p>
   			<p>333333</p>
   			</th>
   			<th scope="col">
   			<p>444444</p>
   			<p>555555</p>
   			</th>
   		</tr>
   	</thead>
   	<tbody>
   		<tr>
   			<td>
   			<p>bbbbbbbb</p>
   			<p>ccccccccc</p>
   			</td>
   			<td>
   			<p>ddddddddd</p>
   			<p>eeeeeee</p>
   			</td>
   			<td>
   			<p>ffffffffffff</p>
   			<p>gggggggggg</p>
   			</td>
   		</tr>
   	</tbody>
   </table>
   <p dir="ltr">&nbsp;</p>
   

2. Right click table.
3. Select Table Properties.

Expected result

Headers option shows "None".

Actual result

Headers option shows "First".

Other details (browser, OS, CKEditor version, installed plugins)

Problem can be reproduced in every browser starting from CKEditor 3.0.

[Jakub Ś]

Similar tickets concerning headers (there are few more related to headers):#9189, #9743, #10682.