we return a set of headers not more. This enables FTP operations that don't
transfer any data, only perform FTP commands.

directory part is now stripped off and only the actual file name part will be
used

set.upload to FALSE or else we might still get an upload if the previous
operation was an upload!

is not dealt with when we find an end-of-response line, as there might be
important stuff even after the correct line. So on subsequent invokes, the
cached data must be used!

responses at once, to excerise the part of curl to make sure it can cache
(parts of) responses properly.