`http_proxy` bug with `starlette.responses.RedirectResponse`

[wzh1994]

When using requests with the http_proxy environment variable set, and explicitly passing proxies={'http': None, 'https': None} to bypass the proxy, the first request correctly avoids using the proxy. However, if the request returns a redirect (e.g. 3xx), the redirected request incorrectly picks up the proxy settings from the environment, causing the request to fail.

When passing proxies={'http': None, 'https': None} to a request, both the original and any redirected requests should bypass the proxy and not use the http_proxy environment variable.

Only the original request respects the proxies={'http': None, 'https': None} setting. The redirected request ignores it and uses the proxy from the environment variable, leading to connection errors if the target is not proxy-accessible.

Reproduction Steps

import os
import requests

# Set environment variable proxy (simulating a typical corporate environment)
os.environ['http_proxy'] = 'http://some.invalid.proxy:8080'

# Target URL that redirects to another domain
url = "http://httpbin.org/redirect-to?url=http://example.com"

# Explicitly disable proxy
resp = requests.get(url, proxies={'http': None, 'https': None})
print(resp.status_code)

Suggested Fix

In sessions.py line 316:

new_proxies = resolve_proxies(prepared_request, proxies, self.trust_env)
should be updated to:
new_proxies = resolve_proxies(prepared_request, proxies, self.trust_env if proxies is None else False)

This ensures that when proxies is explicitly passed in by the user (even as None), environment proxies are not used for redirects.

[wzh1994]

For the time being, I solved the issue by manually setting the trust_env attribute of the Session object to False in the modified request function.

Refer： https://github.com/LazyAGI/LazyLLM/pull/548/files#diff-b02a502a018fbdf49a0af37c6f8c2e971bbd850f4cad1ca6cca54da63cf1ca1cR26