Rake failures in assert_tag in Typo 4.0.2 on Dreamhost

(cross-posted in the old Ruby on Rails google group -- sorry!)

I've got Typo 4.0.2 running beautifully on my Dreamhost server, but
there are these nagging failures when I run rake that are annoying me.
Everything seems to be working just fine from the front-end, so it's
not super critical. But it bugs me that I can't get rake to pass.
What's even wierder is that the tests pass 100% on my local machine

It looks like all the errors have to do with assert_tag. By looking at
the errors from rake I don't see anything wrong, so I think could
assert_tag be broken in my installation of rails?

Here's three of the 7 failures that I get consistently (the other ones
are more of the same and are really long):

1) Failure:
expected tag, but no tag found matching {:child=>"An extension",
:after=>{:child=>"A body", :after=>{:content=>nil, :tag=>"h4"},
:tag=>"p"}, :tag=>"p"} in:
"<h4>A title</h4>\n\n<p>A body</p><p>An extension</p>\n".
<nil> is not true.

2) Failure:
expected tag, but no tag found matching {:child=>"A body",
:after=>{:content=>nil, :tag=>"h4"}, :tag=>"p"} in:
"<h4></h4>\n\n<p>A body</p>\n".
<nil> is not true.

3) Failure:
expected tag, but no tag found matching {:child=>"An extension",
:after=>{:content=>nil, :tag=>"h4"}, :tag=>"p"} in:
"<h4></h4>\n\n<p>An extension</p>\n".
<nil> is not true.

Anybody have a clue? I have searched and searched and haven't seen
anything about this.