Response.make_conditional(..., accept_ranges=True) does not send Accept-Ranges header early enough #3108

#1711 refactored the _process_range_request method. Before, it used to set Accept-Ranges as the first thing it did. Now, it only sets Accept-Ranges when sending a response to a Range request, which defeats the point of that header (which is to advertise support for range requests, so it's not useful if the client is already doing a range request).

basic repro:

# /// script
# dependencies = [
#     "werkzeug==3.1.5",
# ]
# ///
from werkzeug.wrappers import Request, Response
from werkzeug.serving import run_simple
from werkzeug.wsgi import wrap_file
import io

def application(environ, start_response):
    text = b"Hello world!"
    wrap = wrap_file(environ, io.BytesIO(text))
    response = Response(wrap, mimetype='text/plain')
    response.set_etag('test')
    response.make_conditional(environ, accept_ranges=True, complete_length=len(text))
    return response(environ, start_response)


run_simple('127.0.0.1', 5000, application)

when making a request against this with curl -i http://127.0.0.1:5000/, there is no Accept-Ranges header. It only appears when doing a range request like curl -i http://127.0.0.1:5000/ -H "Range: bytes=0-7". Note that when changing the version constraint to werkzeug<1.0 (before #1711 was merged), we do see Accept-Ranges in the response to the basic request.

The fix would be to move the setting of Accept-Ranges back to the very beginning of _process_range_request.

Environment:

• Python version: 3.13.12
• Werkzeug version: 3.1.5