Patch #1608267: fix a race condition in os.makedirs() is the directory

to be created is already there.
 (backport from rev. 52972)

Lib/os.py

@@ -25,6 +25,8 @@ and opendir), and leave all pathname manipulation to os.path
 
 import sys
 
+from errno import ENOENT, ENOTDIR, EEXIST
+
 _names = sys.builtin_module_names
 
 # Note:  more names are added to __all__ later.
@@ -160,7 +162,12 @@ def makedirs(name, mode=0777):
     if not tail:
         head, tail = path.split(head)
     if head and tail and not path.exists(head):
-        makedirs(head, mode)
+        try:
+            makedirs(head, mode)
+        except OSError, e:
+            # be happy if someone already created the path
+            if e.errno != EEXIST:
+                raise
         if tail == curdir:           # xxx/newdir/. exists if xxx/newdir exists
             return
     mkdir(name, mode)
@@ -359,8 +366,6 @@ def execvpe(file, args, env):
 __all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"])
 
 def _execvpe(file, args, env=None):
-    from errno import ENOENT, ENOTDIR
-
     if env is not None:
         func = execve
         argrest = (args, env)

Misc/NEWS

@@ -118,6 +118,9 @@ Extension Modules
 Library
 -------
 
+- Patch #1608267: fix a race condition in os.makedirs() is the directory
+  to be created is already there.
+
 - Patch #1610437: fix a tarfile bug with long filename headers.
 
 - Patch #1472877: Fix Tix subwidget name resolution.