If a cache item is corrupt, ignore and delete it.

diff --git a/SDURLCache b/SDURLCache
index 0544cf53dd9cfdb33d55df13668869b341d32535..964596be054e329b422f96fe8d0a01049ceb0551 160000 (submodule)
--- a/SDURLCache
+++ b/SDURLCache
@@ -1 +1 @@
-Subproject commit 0544cf53dd9cfdb33d55df13668869b341d32535
+Subproject commit 964596be054e329b422f96fe8d0a01049ceb0551