Blockquote Bug in 1.5.3?

I’m setting up a new blog using WP 1.5.3 and I copied a few posts from another blog of mine that’s running 1.5.2 as dummy content to make sure it all looks right. I have some nested blockquotes in one of the posts like this:

Introductory paragraph. The following is a quote with two quotes embedded in it:

<blockquote>Here is the first bit of text.

<blockquote>Here is the bit of text it quotes first</blockquote>

Then another bit of text.

<blockquote>Then the second bit of text it quotes.</blockquote></blockquote>

And on the 1.5.2 blog this displays perfectly, but on the 1.5.3 one it’s being saved as this:

Introductory paragraph. The following is a quote with two quotes embedded in it:

<blockquote>Here is the first bit of text.

</blockquote><blockquote>Here is the bit of text it quotes first</blockquote>

Then another bit of text.

<blockquote>Then the second bit of text it quotes.</blockquote>

So it doesn’t seem to be going into the database like I want it. If I click “Save and continue editing” in the post composition page it applies this change to the code. It’s really annoying. Is this a bug with 1.5.3 or is there a way to fix this?