Resuming a download of an already downloaded document, that is trying to get

Resuming a download of an already downloaded document, that is trying to get
a range of a document beyond its size, caused libcurl to "hang" until the
server closed the connection and then it returned error 18.

This is bad. This way, we don't return any error at all, which isn't nice
either, as we need to alert the app somehow that the request range was out
of size.