fetch on pkg.freebsd.org does not handle If-Modified-Since properly

Hi,

I have a script which regularly fetch some files from pkg.freebsd.org for keeping statistics. (https://www.klop.ws/pkgstats/pkg-age.html)

The command it executes is: "fetch -vv -o /home/ronald/verify_pkgs.sh/downloads/FreeBSD:13:armv7_latest_data.pkg --if-modified-since=/home/ronald/verify_pkgs.sh/downloads/FreeBSD:13:armv7_latest_data.pkg https://pkg.freebsd.org/FreeBSD:13:armv7/latest/data.pkg"

Mind that the request header If-Modified-Since has the exact same time as the response header Last-Modified.
If-Modified-Since: Sun, 05 Oct 2025 04:47:06 GMT
Last-Modified: Sun, 05 Oct 2025 04:47:06 GMT

Still the response says HTTP/1.1 200 OK instead of 304 Not Modified.

I've had this in my projects if the File.lastModified() returns a date with milliseconds, while the http-request time always uses 0 for milliseconds. In that case the file is always newer.
NB: not all fetch requests have this behaviour. Some give a 304 response.

Anyway, maybe the cause is something else. Would be nice to fix this optimization.

Here the verbose output of the fetch command:
scheme:   "https"
user:     ""
password: ""
host:     "pkg.freebsd.org"
port:     "0"
document: "/FreeBSD:13:armv7/latest/data.pkg"
---> pkg.freebsd.org:443
resolving server address: pkg.freebsd.org:443
SSL options: 82004850
Peer verification enabled
Using OpenSSL default CA cert file and path
Verify hostname
TLSv1.3 connection established using TLS_AES_128_GCM_SHA256
Certificate subject: /CN=pkg.freebsd.org
Certificate issuer: /C=US/O=Certainly/CN=Certainly Intermediate R1
requesting https://pkg.freebsd.org/FreeBSD:13:armv7/latest/data.pkg
>>> GET /FreeBSD:13:armv7/latest/data.pkg HTTP/1.1
If-Modified-Since: Sun, 05 Oct 2025 04:47:06 GMT
>>> If-Modified-Since: Sun, 05 Oct 2025 04:47:06 GMT
>>> Host: pkg.freebsd.org
>>> Accept: */*
>>> User-Agent: fetch libfetch/2.0
>>> Connection: close
>>>
<<< HTTP/1.1 200 OK

<<< Connection: close

<<< Content-Length: 9137918

<<< Server: nginx

content length: [9137918]
<<< Content-Type: application/octet-stream

<<< Last-Modified: Sun, 05 Oct 2025 04:47:06 GMT

<<< ETag: "68e1f84a-8b6efe"

last modified: [2025-10-05 04:47:06]
<<< X-Content-Type-Options: nosniff

<<< X-XSS-Protection: 1; mode=block

<<< X-Frame-Options: SAMEORIGIN

<<< Accept-Ranges: bytes

<<< Via: 1.1 varnish, 1.1 varnish

<<< Date: Sat, 10 Jan 2026 11:04:02 GMT

<<< X-Served-By: cache-chi-kigq8000150-CHI, cache-ams2100142-AMS

<<< X-Cache: MISS, MISS

<<< X-Cache-Hits: 0, 0

<<< X-Timer: S1768043043.639628,VS0,VE106

<<< Cache-Control: no-cache,no-store,max-age=0

<<<

offset 0, length -1, size -1, clength 9137918
local size / mtime: 9137918 / 1759639626
remote size / mtime: 9137918 / 1759639626
/home/ronald/verify_pkgs.sh/downloads/FreeBSD:13:armv7_latest_d        8923 kB   20 MBps    01s


Regards,
Ronald.