* apt-pkg/contrib/fileutl.h:

* apt-pkg/contrib/fileutl.h:
  - store the offset in the internal fd before calculate size of
    the zlib-handled file to jump back to this place again

It jumped back to the position of the content - which is wrong as
the internal fd is compressed and even reseting to the beginning of
the file doesn't work as zlib uses an internal buffer, so while we
might haven't read anything yet zlib might have done so already…