Wordpress deals incorrectly with the q tag with regard to subquotes

[Christiaan]

When using the <q> element for quotemarks there is a problem doing subquotes, "as in 'this is a' subquote."

Typically a subquote would be done like this:
<q>as in <q>this is a</q> subquote.</q>

But Wordpress, presumably wanting to close what it thinks are open tags, saves it like this:
<q>as in </q><q>this is</q> a subquote.

So you end up with this:
"as in ""this is" a subquote.

Instead of this:
"as in 'this is a' subquote."

The problem also exists for <blockquote>

Updated version to 2.0 - problem still exists.

Updated to 2.1

Tested in r4914, and the nested <q>'s work fine.