Fixup cache restoring context

python/dune/perftool/generation/context.py

@@ -44,6 +44,7 @@ class _CacheRestoringContext(object):
 
     def __exit__(self, exc_type, exc_value, traceback):
         for i, c in self.cache.items():
+            i._memoize_cache = {}
             for k, v in c.items():
                 i._memoize_cache[k] = v