From 7a018615b63a3319714b185d95cefb58eee07d26 Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Mon, 17 Feb 2020 12:27:25 -0500
Subject: [PATCH] Extract existing names lookup into a variable once again.
 Fixes #43.

---
 zipp.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/zipp.py b/zipp.py
index 2ede259..4122b73 100644
--- a/zipp.py
+++ b/zipp.py
@@ -68,11 +68,12 @@ class CompleteDirs(zipfile.ZipFile):
     @staticmethod
     def _implied_dirs(names):
         parents = itertools.chain.from_iterable(map(_parents, names))
+        # Cast names to a set for O(1) lookups
+        existing = set(names)
         # Deduplicate entries in original order
         implied_dirs = OrderedDict.fromkeys(
             p + posixpath.sep for p in parents
-            # Cast names to a set for O(1) lookups
-            if p + posixpath.sep not in set(names)
+            if p + posixpath.sep not in existing
         )
         return implied_dirs