Apache reverse-proxy closing my connection?

[warlord-DPNOqEs/LNQ at public.gmane.org (Derek Atkins)]

Hey,

I'm trying to setup Apache as a reverse proxy but it looks like Apache
is improperly closing my connection.  From the wireshark output I see
the following transactions which clearly show that the connection
*should* be kept alive, but the proxy is adding a "Connection: close" to
the final response:

CLIENT -> PROXY:

GET /Pages/Default.aspx HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.5.12-1.fc12 Firefox/3.5.12
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,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
Cookie: WSS_KeepSessionAuthenticated=80
Pragma: no-cache, no-cache
Cache-Control: no-cache, no-cache
Authorization: NTLM TlRMTVNTUAABAAAAB4IIAAAAAAAAAAAAAAAAAAAAAAA=

PROXY -> BACKEND SERVER:

GET /Pages/Default.aspx HTTP/1.1
Host: 172.16.64.10
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.5.12-1.fc12 Firefox/3.5.12
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Cookie: WSS_KeepSessionAuthenticated=80
Pragma: no-cache, no-cache
Cache-Control: no-cache, no-cache
Authorization: NTLM <auth data here>
X-Forwarded-For: 127.0.0.1
X-Forwarded-Host: 127.0.0.1
X-Forwarded-Server: pgpdev.ihtfp.org
Connection: Keep-Alive

BACKEND SERVER -> PROXY:


HTTP/1.1 401 Unauthorized
Content-Length: 1539
Content-Type: text/html
Server: Microsoft-IIS/6.0
WWW-Authenticate: NTLM <challenge data here>
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 12.0.0.6421
Date: Fri, 13 May 2011 20:14:24 GMT

<data>

But finally the PROXY -> CLIENT:

HTTP/1.1 401 Unauthorized
Date: Fri, 13 May 2011 20:14:24 GMT
Server: Microsoft-IIS/6.0
Content-Length: 1539
Content-Type: text/html; charset=UTF-8
WWW-Authenticate: NTLM <challenge data here>
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 12.0.0.6421
Connection: close

<data>


Note the "Connection: close" in the Proxy -> client response!  However
the response from the backend server to the proxy clearly is a
keep-alive, as it's an HTTP/1.1 and doesn't have a Connection header.
Is there something missing from my Apache configuration?  Is this a bug
in Apache (I'm using version 2.2.15)?  Here's the relevant configuration
(for my testing purposes, I've tried setting many different Proxy
options to try to get it working):

ProxyRequests off
ProxyPass / http://172.16.64.10/ timeout=300 disablereuse=on nocanon keepalive=on
ProxyPassReverse http://172.16.64.10/ /
ProxyPassReverseCookieDomain 172.16.64.10 127.0.0.1
ProxyVia off

<Location />
ProxyPassReverse /
RequestHeader	 unset	Accept-Encoding
</Location>

Any suggestions?

Thanks!

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord-DPNOqEs/LNQ at public.gmane.org                        PGP key available