fix: dont retrieve from store until accessing file

Author: Amnesthesia

lib/carrierwave/uploader/store.rb

@@ -125,7 +125,8 @@ def retrieve_from_store!(file_identifier)
         with_callbacks(:retrieve_from_store, file_identifier) do
           # We can't retrieve the file if we have no identifier
           # to retrieve it with. Identifier should be assigned
-          # when setting up the uploader
+          # when setting up the uploader, or when caching,
+          # or storing a new file
           next unless file_identifier
           @file = storage.retrieve!(file_identifier)
           @identifier = file_identifier