Bugbear: Add Mutable Parameter fixes (#9682)

Part of #9366

Adds in fixes for B006 and B008, both relating to mutable parameter lint errors.

Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>

2 files changed, 6 insertions, 4 deletions

diff --git a/synapse/http/client.py b/synapse/http/client.py

index e691ba6d88..f7a07f0466 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -297,7 +297,7 @@ class SimpleHttpClient:
     def __init__(
         self,
         hs: "HomeServer",
-        treq_args: Dict[str, Any] = {},
+        treq_args: Optional[Dict[str, Any]] = None,
         ip_whitelist: Optional[IPSet] = None,
         ip_blacklist: Optional[IPSet] = None,
         use_proxy: bool = False,
@@ -317,7 +317,7 @@ class SimpleHttpClient:
 
         self._ip_whitelist = ip_whitelist
         self._ip_blacklist = ip_blacklist
-        self._extra_treq_args = treq_args
+        self._extra_treq_args = treq_args or {}
 
         self.user_agent = hs.version_string
         self.clock = hs.get_clock()
diff --git a/synapse/http/proxyagent.py b/synapse/http/proxyagent.py

index 16ec850064..ea5ad14cb0 100644
--- a/synapse/http/proxyagent.py
+++ b/synapse/http/proxyagent.py
@@ -27,7 +27,7 @@ from twisted.python.failure import Failure
 from twisted.web.client import URI, BrowserLikePolicyForHTTPS, _AgentBase
 from twisted.web.error import SchemeNotSupported
 from twisted.web.http_headers import Headers
-from twisted.web.iweb import IAgent
+from twisted.web.iweb import IAgent, IPolicyForHTTPS
 
 from synapse.http.connectproxyclient import HTTPConnectProxyEndpoint
 
@@ -88,12 +88,14 @@ class ProxyAgent(_AgentBase):
         self,
         reactor,
         proxy_reactor=None,
-        contextFactory=BrowserLikePolicyForHTTPS(),
+        contextFactory: Optional[IPolicyForHTTPS] = None,
         connectTimeout=None,
         bindAddress=None,
         pool=None,
         use_proxy=False,
     ):
+        contextFactory = contextFactory or BrowserLikePolicyForHTTPS()
+
         _AgentBase.__init__(self, reactor, pool)
 
         if proxy_reactor is None: