Conditional request not honored in Includes - apache

Question

I'm trying to dynamically concatenate a bunch of javascript files into a single file using the INCLUDE filter. The include.shtml.js test script is
<!--#include virtual="/static/script2.js" -->
<!--#include virtual="/static/script1.js" -->
The virtual server config has both SSIETag and SSILastModified set to On for that file
<VirtualHost *:80>
ServerName test.dkt
ServerAlias test.com
UseCanonicalName Off
ErrorLog logs/test.dkt-error_log
CustomLog logs/test.dkt-access_log combined
LogLevel info
FileEtag All
AddType application/javascript .js
DocumentRoot /var/www/html/test.com
<Directory /var/www/html/test.com>
Options -Indexes
ExpiresActive Off
ExpiresDefault "access plus 1 years"
Header append Cache-Control "public"
Order deny,allow
Allow from all
</Directory>
<Directory /var/www/html/test.com/static>
<FilesMatch "\.shtml\.js$">
SSIETag On
SSILastModified On
Options +Includes
SetOutputFilter INCLUDES
</FilesMatch>
</Directory>
</VirtualHost>
It correctly serves the concatenated scripts but is always a full 200 OK in instead of a 304 Not Modified. The Firebug log
Response Headers
HTTP/1.1 200 OK
Date: Fri, 24 Jan 2014 16:57:12 GMT
Server: Apache/2.2.15 (CentOS)
Last-Modified: Fri, 24 Jan 2014 16:53:32 GMT
Etag: "460bbc-5c-4f0ba32b7447d"
Accept-Ranges: bytes
Vary: Accept-Encoding
Content-Encoding: gzip
Cache-Control: public
Content-Length: 40
Connection: close
Content-Type: application/javascript
Request Headers
GET /static/include.shtml.js HTTP/1.1
Host: test.dkt
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:26.0) Gecko/20100101 Firefox/26.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: pt-br,en-us;q=0.9,es;q=0.7,en;q=0.6,zh-tw;q=0.4,ar-sa;q=0.3,ar;q=0.1
Accept-Encoding: gzip, deflate
DNT: 1
Connection: keep-alive
If-Modified-Since: Fri, 24 Jan 2014 16:53:32 GMT
If-None-Match: "460bbc-5c-4f0ba32b7447d"
Cache-Control: max-age=0
Is there a hard coded restriction on conditional requests for the INCLUDE filter?
I'm aware that I should "touch" the including script whenever there is a change in any of the included scripts. The Apache version is 2.2 running in Centos 6
EDIT
Using the #covener answer I made it work setting the group execute permission of the file and adding the XBitHack full directive

Answer 1

Even though you've opted into the etags, it seems you need to separately enable xbithack to allow a 304 to be generated (ap_meets_conditions in the core checks no_local_copy flag referenced in mod_include
http://httpd.apache.org/docs/current/mod/mod_include.html#xbithack
/* When our xbithack value isn't set to full or our platform isn't
* providing group-level protection bits or our group-level bits do not
* have group-execite on, we will set the no_local_copy value to 1 so
* that we will not send 304s.
*/
if ((conf->xbithack != XBITHACK_FULL)
|| !(f->r->finfo.valid & APR_FINFO_GPROT)
|| !(f->r->finfo.protection & APR_GEXECUTE)) {
f->r->no_local_copy = 1;
}

Answer 2

When having
SSILastModified on
XBitHack full
together in configuration file, the setting "SSILastModified On" is a silent misconfiguration, because whether "SSILastModified" is on or not, it does not change any program behavior.
By tracking back to the source code of Apache, we can see the root cause of this misconfiguration is that the semantics enabled by "Xbithack Full" implicitly overwrite the semantics enabled by "SSILastModified On".
if (conf->lastmodified > 0) {
... {
ap_update_mtime(r, r->finfo.mtime);
ap_set_last_modified(r);}}
else if (((conf->xbithack == XBITHACK_FULL ||
(conf->xbithack == XBITHACK_UNSET &&
DEFAULT_XBITHACK == XBITHACK_FULL))
...)) {
ap_update_mtime(r, r->finfo.mtime);
ap_set_last_modified(r);
}
So one possible solution would be just keep this
Xbithack full