Prevent Cache.ensure from throwing an error, while the directory already exists.

1 files changed, 6 insertions, 1 deletions

diff --git a/tools/cache.py b/tools/cache.py
index c316a1fd..ed4fcd24 100644
--- a/tools/cache.py
+++ b/tools/cache.py
@@ -13,8 +13,13 @@ class Cache:
     self.debug = debug
 
   def ensure(self):
-    if not os.path.exists(self.dirname):
+    try:
+      # Use makedirs here, so creating the path is as atomic as possible
       os.makedirs(self.dirname)
+    except os.error, e:
+      # Ignore error for already existing dirname
+      if not os.path.exists(self.dirname):
+        raise e
 
   def erase(self):
     tempfiles.try_delete(self.dirname)