When rebuilding proxies if we do not trust the environment then we do…

… not need to examine proxy information set in the environ.

This fixes a performance regression 5891 but does not fix 5888.

Signed-off-by: David Black <dblack@atlassian.com>

requests/sessions.py

@@ -289,7 +289,9 @@ def rebuild_proxies(self, prepared_request, proxies):
         new_proxies = proxies.copy()
         no_proxy = proxies.get('no_proxy')
 
-        bypass_proxy = should_bypass_proxies(url, no_proxy=no_proxy)
+        bypass_proxy = False
+        if self.trust_env:
+            bypass_proxy = should_bypass_proxies(url, no_proxy=no_proxy)
         if self.trust_env and not bypass_proxy:
             environ_proxies = get_environ_proxies(url, no_proxy=no_proxy)