New Post: colspan

I tried to upgrade to the latest commit to take advantage of recent bug fixes (a big thank you to all who have been working on them) but in doing so, colspans stopped working completely for my table headers. I have no rowspans, only colspans:

<tr class="TableHeaderCells">
     <th style="background-color:#FFFF99;" colspan="4"></th>
     <th style="background-color:#FFFF99;" colspan="7"></th>
     <th style="background-color:#FFFF99;" colspan="5">[Header Text]</th>
</tr>
<tr class="TableHeaderCells">
     <th style="background-color:#FFFF99;" colspan="4"></th>
     <th style="background-color:#FFFF99;" colspan="3">[More Header Text]</th>
     <th style="background-color:#FFFF99;" colspan="4">[Even More Header Text]</th>
     <th style="background-color:#FFFF99;" colspan="3">[Still Even More Header Text]</th>
     <th style="background-color:#FFFF99;" colspan="2">[So Much Header Text]</th>
</tr>

Looking at the document as XML it looks like the colspan attributes are being completely ignored but I can't pinpoint where I am losing them. Any thoughts on where to look?