[IO] Use a unique, temporary name while writing a file to cache
[IO] Use a unique, temporary name while writing a file to cache

This way, if another process requests the file from the cache while
the file is still being written/downloaded, it does not "find" it
and does not read an incomplete file.

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root