In this example above, "c" is parsed as a <th>.. </th> which is broken obviously .. "" in the middle of a line should not parse to a header if there is no "!"-based th at the start of that line.
{| !a <tr><td>b!!c</td></tr> |}
Causes RT diffs here: http://parsoid-lb.eqiad.wikimedia.org/_rt/kowiki/%EB%A7%88%EC%9D%B4%ED%8B%B0_%EB%AA%A8