I'm trying to upgrade using a minimal boot cd.
When I arrived to a http server specification, I made a typo and the install
promptly answered that the stage2.img cannot be retrieved.
After a couple of attempts I got the name of the directory right and the
installer has indeed downloaded the img (the time corresponded to the speed of
my connection).
But when the file has arrived, the loop mount failed: tty3 says:
   LOOP_SET_FD failed: Device or resource is busy.

Is it possible that the fd is busy because of the previous attempt(s)?
Would you be so kind to check this code path?

(When the http URL was correct from the beginning, this loop mount worked.)