When prefetching activities the cache is ignored to get fresh data. This causes some requests to be duplicated:

• When calculating the size of files to download some requests are made that are then repeated when doing the actual prefetch.
• Some activities use helper functions to prevent code duplication in views, but some of these function might end up fetching data that was already fetched.

We need some way to ignore old cache entries but still use the cache for new data during prefetch.