We *might* need to ignore POLLERR messages for UDP sockets, as the
condition is actually temporary and sock_try_event was hiding this.

CreateStubEntry can change the value of This->entries, in which case the
assignment can go to the wrong place. So instead, assign to a temporary
variable, and copy the data back after all CreateStubEntry calls are finished.

This makes sure that an updated file is extracted from the cabinet stream
included in the patch, instead of the original source.