From 58f5565357ed532970772cd55c2d17d1e00198a9 Mon Sep 17 00:00:00 2001
From: Eugenio Lacuesta <eugenio.lacuesta@gmail.com>
Date: Thu, 11 Oct 2018 11:23:12 -0300
Subject: [PATCH] Move MutableChain to scrapy.utils.python

---
 scrapy/core/spidermw.py | 21 +--------------------
 scrapy/utils/python.py  | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/scrapy/core/spidermw.py b/scrapy/core/spidermw.py
index 4268c91d6..d776430e5 100644
--- a/scrapy/core/spidermw.py
+++ b/scrapy/core/spidermw.py
@@ -11,32 +11,13 @@ from scrapy.exceptions import _InvalidOutput
 from scrapy.middleware import MiddlewareManager
 from scrapy.utils.defer import mustbe_deferred
 from scrapy.utils.conf import build_component_list
+from scrapy.utils.python import MutableChain
 
 
 def _isiterable(possible_iterator):
     return hasattr(possible_iterator, '__iter__')
 
 
-class MutableChain:
-    """
-    Thin wrapper around itertools.chain, allowing to add iterables "in-place"
-    """
-    def __init__(self, *args):
-        self.data = chain(*args)
-
-    def extend(self, *iterables):
-        self.data = chain(self.data, *iterables)
-
-    def __iter__(self):
-        return self.data.__iter__()
-
-    def __next__(self):  # py3
-        return self.data.__next__()
-
-    def next(self):  # py2
-        return self.data.next()
-
-
 class SpiderMiddlewareManager(MiddlewareManager):
 
     component_name = 'spider middleware'
diff --git a/scrapy/utils/python.py b/scrapy/utils/python.py
index 732ca13a0..7971b4dde 100644
--- a/scrapy/utils/python.py
+++ b/scrapy/utils/python.py
@@ -9,6 +9,7 @@ import weakref
 import errno
 import six
 from functools import partial, wraps
+from itertools import chain
 import sys
 
 from scrapy.utils.decorators import deprecated
@@ -387,3 +388,23 @@ if hasattr(sys, "pypy_version_info"):
 else:
     def garbage_collect():
         gc.collect()
+
+
+class MutableChain(object):
+    """
+    Thin wrapper around itertools.chain, allowing to add iterables "in-place"
+    """
+    def __init__(self, *args):
+        self.data = chain(*args)
+
+    def extend(self, *iterables):
+        self.data = chain(self.data, *iterables)
+
+    def __iter__(self):
+        return self.data.__iter__()
+
+    def __next__(self):  # py3
+        return self.data.__next__()
+
+    def next(self):  # py2
+        return self.data.next()