Handle other places where we might be unpickling things.

We use pickling in conjunction with caches in these cases so we should
be able to fallback to the uncached behavior if the pickled data is
corrupt in some way.

eg. it's a python 2 pickle we don't know how to read.

openedx/core/djangoapps/content/block_structure/store.py

@@ -207,7 +207,15 @@ class BlockStructureStore(object):
         """
         Deserializes the given data and returns the parsed block_structure.
         """
-        block_relations, transformer_data, block_data_map = zunpickle(serialized_data)
+
+        try:
+            block_relations, transformer_data, block_data_map = zunpickle(serialized_data)
+        except Exception:
+            # Somehow failed to de-serialized the data, assume it's corrupt.
+            bs_model = self._get_model(root_block_usage_key)
+            logger.warning("BlockStructure: Failed to load data from cache for %s", bs_model)
+            raise BlockStructureNotFound(bs_model.data_usage_key)
+
         return BlockStructureFactory.create_new(
             root_block_usage_key,
             block_relations,

openedx/core/lib/edx_api_utils.py

@@ -56,11 +56,16 @@ def get_edx_api_data(api_config, resource, api, resource_id=None, querystring=No
 
         cached = cache.get(cache_key)
         if cached:
-            cached_response = zunpickle(cached)
-            if fields:
-                cached_response = get_fields(fields, cached_response)
+            try:
+                cached_response = zunpickle(cached)
+                if fields:
+                    cached_response = get_fields(fields, cached_response)
 
-            return cached_response
+                return cached_response
+            except Exception:
+                # Data is corrupt in some way.
+                log.warning("Data for cache is corrupt for cache key %s", cache_key)
+                cache.delete(cache_key)
 
     try:
         endpoint = getattr(api, resource)