content type in header is being lost when using a AbstractTransformerBehavior

The content type header information is being lost when using a AbstractTransformerBehavior, please see tha attached example of the problem for an example. It isnt causing a problem on my dev box but on live, it is, because the header info is not getting set tomcat/httpd (I'm assuming) is setting the header to plain/text so that the browser ends up showing the html rather than redering it. Here's a bit more information with wget, as you can see with the first call the content info is missing, with the second call without the AbstractTransformerBehavior being called (it's commented out in BasePage) the [text/html] header is included. I debug through wicket code and found that the issue was with the AbstractTransformerBehavior using a StringResponse whose setContentType() (Response.setContentType()) does nothing!!

============BUG============
$ wget http://localhost:8080/wicket-bug/
-2011-04-22 12:39:19- http://localhost:8080/wicket-bug/
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:8080... failed: Connection refused.
Connecting to localhost (localhost)|127.0.0.1|:8080... connected.
HTTP request sent, awaiting response... 200 OK
Length: 483
Saving to: `index.html'

100%[==============================================================================>] 483 --.-K/s in 0s

2011-04-22 12:39:20 (13.7 MB/s) - `index.html' saved [483/483]

============the transformer commented out============
$ wget http://localhost:8080/wicket-bug/
-2011-04-22 12:40:27- http://localhost:8080/wicket-bug/
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:8080... failed: Connection refused.
Connecting to localhost (localhost)|127.0.0.1|:8080... connected.
HTTP request sent, awaiting response... 200 OK
Length: 479 [text/html]
Saving to: `index.html.1'

100%[==============================================================================>] 479 --.-K/s in 0s

2011-04-22 12:40:28 (13.3 MB/s) - `index.html.1' saved [479/479]