Removed unnecessary setdefault() from CheckRegistry.register().

django/core/checks/registry.py

@@ -40,11 +40,9 @@ class CheckRegistry:
             # or
             registry.register(my_check, 'mytag', 'anothertag')
         """
-        kwargs.setdefault('deploy', False)
-
         def inner(check):
             check.tags = tags
-            checks = self.deployment_checks if kwargs['deploy'] else self.registered_checks
+            checks = self.deployment_checks if kwargs.get('deploy') else self.registered_checks
             checks.add(check)
             return check