Docserver: Attach intro metadata to the template itself, not to an object which

chrome/common/extensions/docs/server2/caching_file_system.py

Index: chrome/common/extensions/docs/server2/caching_file_system.py
diff --git a/chrome/common/extensions/docs/server2/caching_file_system.py b/chrome/common/extensions/docs/server2/caching_file_system.py
index a592dfcb9f9916c8142adeea15337bfa2b694fa7..1a6764e6cc0158b3e7eb081e8202f4548a7f1ee1 100644
--- a/chrome/common/extensions/docs/server2/caching_file_system.py
+++ b/chrome/common/extensions/docs/server2/caching_file_system.py
@@ -79,7 +79,8 @@ class CachingFileSystem(FileSystem):
     else:
       file_version = dir_stat.child_versions.get(file_path)
       if file_version is None:
-        raise FileNotFoundError('No stat found for %s in %s' % (path, dir_path))
+        raise FileNotFoundError('No stat found for %s in %s (found %s)' %
+                                (path, dir_path, dir_stat.child_versions))
       stat_info = StatInfo(file_version)
 
     return stat_info