HTTP:version not working? Breaks CreditCardScrubber irule on chunked sites

I think some (or all?) of the values of HTTP (and other?) commands are cached. I know HTTP::uri is cached, so even if you update it, the value displayed in a subsequent log statement isn't changed. For example:

when HTTP_REQUEST {
   log local0. "original version: [HTTP::version]"
   log local0. "original URI: [HTTP::uri]"
   HTTP::version 1.0
   HTTP::uri /new/uri/
   log local0. "original version: [HTTP::version]"
   log local0. "original URI: [HTTP::uri]"
}

The log output shows no change in either the version or the URI:

Mar 9 11:03:43 tmm tmm[1085]: Rule change_version_uri_rule : original version: 1.1

Mar 9 11:03:43 tmm tmm[1085]: Rule change_version_uri_rule : original URI: /

Mar 9 11:03:43 tmm tmm[1085]: Rule change_version_uri_rule : original version: 1.1

Mar 9 11:03:43 tmm tmm[1085]: Rule change_version_uri_rule : original URI: /

However, a tcpdump of the request received by the BIG-IP versus the request sent to the web server shows both changes were made:

Original request:

GET / HTTP/1.1

Host: test

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB;rv:1.8.1.2) Gecko/20070219 Firefox/2.0.0.2

Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5

Accept-Language: en-gb,en;q=0.5

Accept-Encoding: gzip,deflate

Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive: 300

Connection: keep-alive

Pragma: no-cache

Cache-Control: no-cache

Request sent to the web server:

GET /new/uri/ HTTP/1.0

Host: test

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.2) Gecko/20070219 Firefox/2.0.0.2

Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5

Accept-Language: en-gb,en;q=0.5

Accept-Encoding: gzip,deflate

Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive: 300

Connection: keep-alive

Pragma: no-cache

Cache-Control: no-cache

If you disable HTTP/1.1 on a browser, does the rule work? This should have the same effect as the rule changing 1.1 requests to 1.0: preventing chunked responses.

If you capture a tcpdump of a failure, do you see the BIG-IP using 1.1 to the node? Do you see the node sending chunked responses?

Aaron