From 76cc8d7c247152b0dc9b759cb9ad22d07be27f99 Mon Sep 17 00:00:00 2001
From: Salim Aboubacar <salimaboubacar@gmail.com>
Date: Tue, 31 May 2022 18:42:23 +0200
Subject: [PATCH] Remove side effect in jsonable_encoder to fix failing test

---
 fastapi/encoders.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fastapi/encoders.py b/fastapi/encoders.py
index 6bde9f4ab..254cdc949 100644
--- a/fastapi/encoders.py
+++ b/fastapi/encoders.py
@@ -52,7 +52,7 @@ def jsonable_encoder(
     if isinstance(obj, BaseModel):
         encoder = getattr(obj.__config__, "json_encoders", {})
         if custom_encoder:
-            encoder.update(custom_encoder)
+            encoder = {**encoder, **custom_encoder}
         obj_dict = obj.dict(
             include=include,
             exclude=exclude,