[1.0.X] Fixed #9644: fix a thread sync issue in the locmem cache. Thanks, mrts. Backport of r10333 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10334 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/cache/backends/locmem.py

@@ -58,8 +58,11 @@ class CacheClass(BaseCache):
             self._lock.reader_leaves()
         self._lock.writer_enters()
         try:
-            del self._cache[key]
-            del self._expire_info[key]
+            try:
+                del self._cache[key]
+                del self._expire_info[key]
+            except KeyError:
+                pass
             return default
         finally:
             self._lock.writer_leaves()