From 06f6fbffd4a41b4717aa4931580723eb0d98cc81 Mon Sep 17 00:00:00 2001
From: Brian Curtin <brian@python.org>
Date: Mon, 22 Jul 2013 13:07:52 -0500
Subject: [PATCH] Fix #18530. Remove extra stat call from posixpath.ismount

---
 Lib/posixpath.py | 22 ++++++++++++++--------
 Misc/NEWS        |  3 +++
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index e1d59b6e9f3..73624835020 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -182,18 +182,24 @@ def lexists(path):
 
 def ismount(path):
     """Test whether a path is a mount point"""
-    if islink(path):
-        # A symlink can never be a mount point
-        return False
     try:
         s1 = os.lstat(path)
-        if isinstance(path, bytes):
-            parent = join(path, b'..')
-        else:
-            parent = join(path, '..')
+    except OSError:
+        # It doesn't exist -- so not a mount point. :-)
+        return False
+    else:
+        if stat.S_ISLNK(s1.st_mode):
+            return False
+
+    if isinstance(path, bytes):
+        parent = join(path, b'..')
+    else:
+        parent = join(path, '..')
+    try:
         s2 = os.lstat(parent)
     except OSError:
-        return False # It doesn't exist -- so not a mount point :-)
+        return False
+
     dev1 = s1.st_dev
     dev2 = s2.st_dev
     if dev1 != dev2:
diff --git a/Misc/NEWS b/Misc/NEWS
index 26c629552f7..3391d2c054c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -162,6 +162,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #18530: Remove additional stat call from posixpath.ismount.
+  Patch by Alex Gaynor.
+
 - Issue #18514: Fix unreachable Py_DECREF() call in PyCData_FromBaseObj()
 
 - Issue #9177: Calling read() or write() now raises ValueError, not