most recently opened URL in self.openedurl of the URLopener instance.
This doesn't really work if multiple threads share the same opener
instance!
Fix: openedurl was actually simply the type prefix (e.g. "http:")
followed by the rest of the URL; since the rest of the URL is
available and the type is effectively determined by where you are in
the code, I can reconstruct the full URL easily, e.g. "http:" + url.
retrieving files from the same host and directory, you had to close
the previous instance before opening a new one; and retrieving a
non-existent file would return an empty file. (The latter fix relies
on maybe an undocumented property of NLST -- NLST of a file returns
just that file, while NLST of a non-existent file returns nothing. A
side effect, unfortunately, seems to be that now ftp-retrieving an
*empty* directory may fail. Ah well.)
Sjoerd: add separate administration of temporary files created y
URLopener.retrieve() so cleanup can properly remove them. The old
code removed everything in tempcache which was a bad idea if the user
had passed a non-temp file into it. (I added a line to delete the
tempcache in cleanup() -- it still seems to make sense.)
Jack: in basejoin(), interpret relative paths starting in "../". This
is necessary if the server uses symbolic links.
that multiple retrievals using the same connection will work.
This leaves open the more general problem that after
f = urlopen("ftp://...")
f must be closed before another retrieval from the same host should be
attempted.
