From 986469afbe4e72b95fbaa8b26d805865a5341888 Mon Sep 17 00:00:00 2001
From: Carlton Gibson <carlton.gibson@noumenal.es>
Date: Fri, 1 Dec 2017 11:33:10 +0100
Subject: [PATCH] Make sure `manual_fields` is a list.

(As documented to be)
---
 rest_framework/schemas/inspectors.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/rest_framework/schemas/inspectors.py b/rest_framework/schemas/inspectors.py
index 240b713ac..008d7c091 100644
--- a/rest_framework/schemas/inspectors.py
+++ b/rest_framework/schemas/inspectors.py
@@ -172,7 +172,8 @@ class AutoSchema(ViewInspector):
         * `manual_fields`: list of `coreapi.Field` instances that
             will be added to auto-generated fields, overwriting on `Field.name`
         """
-
+        if manual_fields is None:
+            manual_fields = []
         self._manual_fields = manual_fields
 
     def get_link(self, path, method, base_url):