From b8d448cab205f6358894c99ef68b954e5156d6fa Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Tue, 13 Mar 2018 10:54:01 +0000
Subject: [PATCH] fix multifs listdir bug (#150)

---
 CHANGELOG.md          |  6 ++++++
 fs/_version.py        |  2 +-
 fs/multifs.py         |  3 ++-
 tests/test_multifs.py | 10 ++++++++++
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9c614cd1..237e479a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [2.0.20] - 2018-03-13
+
+### Fixed
+
+- MultiFS.listdir now correctly filters out duplicates
+
 ## [2.0.19] - 2018-03-11
 
 ### Fixed
diff --git a/fs/_version.py b/fs/_version.py
index c016fb0a..aff8a833 100644
--- a/fs/_version.py
+++ b/fs/_version.py
@@ -1,3 +1,3 @@
 """Version, used in module and setup.py.
 """
-__version__ = "2.0.19"
+__version__ = "2.0.20"
diff --git a/fs/multifs.py b/fs/multifs.py
index 3860520c..8caf9228 100644
--- a/fs/multifs.py
+++ b/fs/multifs.py
@@ -5,7 +5,7 @@
 from __future__ import unicode_literals
 from __future__ import print_function
 
-from collections import namedtuple
+from collections import namedtuple, OrderedDict
 from operator import itemgetter
 
 from six import text_type
@@ -203,6 +203,7 @@ def listdir(self, path):
                 exists = True
         if not exists:
             raise errors.ResourceNotFound(path)
+        directory = list(OrderedDict.fromkeys(directory))
         return directory
 
     def makedir(self, path, permissions=None, recreate=False):
diff --git a/tests/test_multifs.py b/tests/test_multifs.py
index 974cdd23..c9dcc747 100644
--- a/tests/test_multifs.py
+++ b/tests/test_multifs.py
@@ -134,3 +134,13 @@ def test_no_writable(self):
     def test_validate_path(self):
         self.fs.write_fs = None
         self.fs.validatepath('foo')
+
+    def test_listdir_duplicates(self):
+        m1 = MemoryFS()
+        m2 = MemoryFS()
+        m1.touch('foo')
+        m2.touch('foo')
+        multi_fs = MultiFS()
+        multi_fs.add_fs('m1', m1)
+        multi_fs.add_fs('m2', m2)
+        self.assertEqual(multi_fs.listdir(u'/'), ['foo'])