From 02eff7ef60466da108b1a33f1e4dc01eec45c99d Mon Sep 17 00:00:00 2001
From: Peter Andersen <peter@porksmash.com>
Date: Mon, 9 Dec 2019 08:54:40 -0800
Subject: Fixed #31073 -- Prevented CheckboxInput.get_context() from mutating
 attrs.

---
 django/forms/widgets.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

(limited to 'django/forms')

diff --git a/django/forms/widgets.py b/django/forms/widgets.py
index 6fe220bea7..d83d63c169 100644
--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -522,9 +522,7 @@ class CheckboxInput(Input):
 
     def get_context(self, name, value, attrs):
         if self.check_test(value):
-            if attrs is None:
-                attrs = {}
-            attrs['checked'] = True
+            attrs = {**(attrs or {}), 'checked': True}
         return super().get_context(name, value, attrs)
 
     def value_from_datadict(self, data, files, name):
-- 
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